Scott McCall, a 16-year-old, and his best friend Stiles go into the woods to find a dead body whose one half is missing, but Stiles' father, the sheriff, catches them. While Scott is returning home, he is bitten by a werewolf. The next day, Scott discovers new abilities like super-hearing and enhanced strength, and is quickly noticed by the team captain Jackson. Scott gets a date to a party with the new girl, Allison, but Stiles warns him that the full moon is upon them and he shouldn't go. Despite the warning, Scott goes to the party, but starts getting pains from his first transformation and flees. Scott later begins to view Derek Hale, a mysterious young man who drove Allison home from the party, as a threat as he thinks Derek is the werewolf who bit him. When Scott is shot in the arm with an arrow by three werewolf hunters in the woods, he is saved by Derek, who reveals to him that he is a werewolf too. The next morning at school, Scott apologizes to Allison for leaving her at the party and finds out that one of the werewolf hunters is actually Allison's father.

Scott tells Stiles that Allison's father was one of the werewolf hunters who tried to shoot him. Later, Scott hurts Jackson badly during lacrosse practice and starts transforming. Stiles take Scott to the locker room where Scott attacks him, but Stiles calms him down. That night, Derek tells Scott not to show up at the game on Saturday night or he will transform. Coach Finstock however, tells Scott that he's out if he doesn't play. When Scott goes to Derek's house, he smells the other half of the dead body buried nearby. Scott and Stiles report Derek to the sheriff and Derek is arrested. Scott makes the winning shot at the game and starts transforming. He runs to the locker room where Allison quickly comes for him. Scott manages to control himself and they kiss. Stiles breaks the news that Derek has been released from jail since the body was ripped by an animal and the body is of Laura Hale: Derek's sister. Jackson finds Scott's pierced glove in the field and looks at it with confusion, as Derek watches from behind.

Scott and Allison are making out in a school bus, the adrenaline rush making Scott turn into a werewolf. He proceeds to attack Allison. The events turn out to be a dream. At school, Scott and Stiles see a bloodied school bus outside and Scott worries that he actually killed Allison, but is relieved to see her alive and well. In class, Scott and Stiles see the real victim, deeply injured, from the bus attack. Worried, Scott turns to Derek for help on controlling his animal side. Derek agrees to help as long as Scott promises him an unknown favor. He then sends Scott to the bus where he discovers (through flashbacks) that he didn't attack the bus driver but was trying to help him instead. Feeling better, Scott goes on a group date with Allison, Lydia and Jackson, where Jackson's suspicions of Scott increase. Stiles informs Scott that the bus driver has died from his wounds. Angry, Scott heads to Derek's house where they fight as werewolves until Derek reveals to Scott that he wasn't the one who bit him. Scott learns there is another wolf, a powerful Alpha werewolf, who actually bit him. Derek hopes to use Scott's connection to the Alpha werewolf to find him and for Scott to help (the promised favor).

A woman driving at night is followed by an Alpha werewolf that tries to kill her. The woman shoots at it with her gun. Derek is in the shadows, trying to follow the Alpha werewolf, but is shot in the arm with a wolfsbane bullet by the woman. Scott overhears Allison's dad and the woman, Allison's aunt Kate, saying Derek has 48 hours to live. The next day, Derek goes looking for Scott at his school and asks Jackson where he is. Jackson irritates him instead and Derek grabs the back of his neck, causing scratches from his wolf claws on Jackson's skin. After school, Stiles and Scott see Derek and he tells them he needs a wolfsbane bullet like the one the hunter used on him. Stiles is left with Derek while Scott goes to Allison's house to find the bullet. Scott is forced to stay for an awkward dinner while trying to find the bullet, and Stiles, having a hard time taking care of Derek, takes him to the vet's office. With Derek's health rapidly declining, Derek plans to have Stiles cut his arm off if they run out of time, since he will die if the wolfsbane reaches his heart. Scott finds a wolfsbane bullet in Kate's bag and takes one, making it to the vet's office right before Stiles starts cutting Derek's arm. Derek uses the wolfsbane in the bullet to supernaturally heal his wound. Scott admits the hunters of Allison's family seem like good people. To prove him wrong, Derek takes Scott to see his badly burned uncle, solemnly explaining that a fire killed his entire family 6 years ago, started by hunters who went against their own rules; it is hinted that Kate was one of those hunters.

Lydia and Jackson are outside a video store, trying to decide on a movie. While Lydia stays in the car, Jackson goes inside and finds the clerk with his throat ripped out. Horrified, Jackson hears growling and hides behind one of the shelves before peering out to see the eyes of the Alpha werewolf. The Alpha werewolf knocks down the shelves, pinning Jackson to the floor. The Alpha werewolf almost attacks him but notices the claw marks on the back of Jackson's neck left by Derek. The Alpha werewolf then runs off. Scott and Derek are up on the roof of the video store, where Derek shows Scott what the Alpha werewolf has done. He reminds Scott that the Alpha werewolf will kill him unless they team up to fight it. That morning, Allison receives a necklace with her family crest on it from Kate as a birthday present. Scott and Allison skip school for her birthday. Stiles visits Lydia at her home, loopy on pills, when she is absent from school, and finds a video on her phone of the Alpha at the video store. He eventually decides to delete the video. Derek must deal with Kate and other hunters in a wild confrontation. At Parent-Teacher Night, Allison's father and Scott's mother find out that the two have skipped school. Just then, an unseen animal runs through the parking lot. There is chaos before Allison's father shoots it. The crowd surrounds the dead animal, which turns out to be a mountain lion.

Scott is chased by a werewolf in a parking garage. The werewolf turns out to be Derek, who was testing Scott's skills. Scott asks Derek to teach him how to control his changes and Derek agrees to do so if he stays away from Allison, as she is a distraction. Scott agrees but goes to see Allison anyway. He then has a run-in with the Alpha werewolf, who draws a spiral on his window, similar to the one on Derek's sister, Laura's grave. Scott tells Derek about the spiral, which disturbs Derek. Since Scott's short temper is what sets off his transformation, Stiles decides to help Scott control his anger. They both realize that Allison keeps Scott calm. Jackson, disturbed by the claw marks on his neck, has strange hallucinations. Derek visits his burnt uncle and asks about the Alpha werewolf but leaves after no response. He finds an article about a dead deer with a spiral etched into its fur on his car, learns the town vet dealt with the animal, and visits him. When the vet lies, Derek angrily tries to get the truth from him. Scott stops him just as Derek knocks the vet out. He tells Derek to meet him tonight at school, where he and Stiles sneak in to use the PA system so Scott can call the Alpha werewolf. Derek arrives with the unconscious vet in his car. After Scott calls the Alpha werewolf, the boys go outside, where they notice the vet is gone from Derek's car. Derek is then lifted by the Alpha werewolf and thrown against the wall, knocking him out. The Alpha then goes after Scott and Stiles, who lock themselves in the school, panicked and unsure if Derek is still alive.

Locked in the school, Scott and Stiles try to figure out how to escape from the Alpha werewolf safely. The Alpha werewolf keeps them from leaving and murders the janitor. Allison goes to the school with Jackson and Lydia after she gets a mysterious text from Scott saying to meet him at the school. Soon enough, everyone gets trapped inside the cafeteria. Scott reveals he never sent Allison any text. Jackson, Lydia and Allison demand to know what's going on. Not knowing what to say, Scott lies that Derek is the one after them. Stiles calls his father, the sheriff, despite wanting to keep him safe. The group flees into a science classroom, where they find a locked door, which leads to a fire escape. Scott looks for the janitor's body to get the keys. He follows the janitor's scent to the gym, and finds the body under the bleachers. He comes face-to-face with the Alpha werewolf, who howls, causing Scott to transform painfully. Jackson also reacts to the howl, due to his scratches. Scott makes his way back to the classroom as a wolf but is stopped by Allison's voice. He changes back just as Stiles' father arrives with the police. Outside, safe and free, Scott sees the vet, mysteriously okay. Scott tells Stiles that the Alpha werewolf never planned to kill them at all; the Alpha werewolf actually wanted Scott to kill everyone himself so that he could join the Alpha werewolf's pack. Scott admits this is dangerous because in werewolf form, he actually wanted to kill them all. Allison breaks up with Scott, feeling she can't trust him.

Stiles takes Scott into the woods to get drunk in an effort to comfort him after his break-up with Allison. Two men come and take the bottle, only for Scott, influenced by the coming full moon, to get angered. The men are killed by the Alpha werewolf shortly after. At school, Scott begins showing bizarre behavior unlike himself and hallucinating, results of the coming full moon. Stiles and Scott plan to keep Scott locked up during the full moon, for fear that he may kill someone under its influence. Prior to lacrosse practice, Stiles asks Scott if he can ask Lydia if she likes him (Stiles). However Scott approaches Lydia only to ask if Allison still likes him (Scott); Lydia shifts the conversation and she and Scott make out. Scott later lies to Stiles, and is incredibly violent during practice. Allison and Jackson bond and talk, both agreeing that Derek was not their attacker. That evening, Stiles handcuffs a predatory Scott to a radiator to protect him from himself and to get revenge on him kissing Lydia. Scott goes wild, transforms and escapes. Just as he is about to attack Jackson and Allison, Derek, who is revealed to be alive, subdues him. The Argents conclude that there's a younger Beta werewolf alongside Derek. Scott, now back to normal and scared about what is happening to him, asks if there's a cure. Derek confirms that there might be: to kill the one who bit him. Jackson finds a claw-nail on his car, left by Scott, and realizes that it matches the hole in Scott's pierced glove that he found in Second Chance at First Line.

Jackson discovers Scott's secret and wants to become a werewolf too. Jackson becomes closer with Allison, dumping Lydia in the process. Derek is on the run from police as he is a suspect in the murders since Scott put the blame on him for the events of Night School. Stiles' father interrogates Scott's chemistry teacher, who guiltily explains that he had met Kate years before and explained to her how to set a fire after she got him drunk, and that a few days after, the fire that killed Derek's family occurred. Although he doesn't remember Kate, he draws the Argent family crest and gives it to Derek as a lead. Scott tells Derek he saw the crest on Allison's necklace and Derek asks him to find the necklace, as it has to do with her family's secret. Scott sneaks into Allison's room and finds the necklace in the pages of an old book that has to do with werewolves. Before Scott leaves, he is caught by Allison's father, who asks Scott how he knows Derek Hale. Scott explains everything he did while they were locked in the school was to protect Allison, which Allison overhears. Stiles and Derek trace the sender of the mysterious text message from Night School to the hospital from Melissa McCall's account. Stiles goes to the hospital with Derek. With a nasty shock, they find out that Derek's uncle is in fact the Alpha werewolf, who has been responsible for all the murders.

Stiles uses his father's research to get answers about the Alpha werewolf's victims. Apparently, the Alpha werewolf has been killing only the ones who were involved with the fire that killed the Hale family. Jackson is suspected to be one of the Beta werewolves and Allison's father tries to get the truth out of him. Scott is angered by this but Jackson is still keen on becoming a werewolf. Derek and his uncle tell Scott they want him to join the pack and Scott is shocked that Derek is suddenly on the Alpha werewolf's side. The Alpha werewolf punctures Scott's neck, showing him what really happened during the fire and the murders through flashbacks. While looking for her family crest necklace, Allison finds the sharp end of an arrow left behind by Kate and tries it out in the woods with Lydia. She shoots Scott with a taser, thinking him to be an intruder. She apologizes and Scott reveals that he was there to return her necklace. Allison later visits Scott's house, wanting to talk to him. At the same time, they see that Scott's mom, Melissa, is preparing for a date. Scott opens the door to see that Melissa's date is the Alpha werewolf. The Alpha werewolf plans to convert Melissa into a werewolf as a means of coercing Scott to join the pack. Scott leaves Allison in his bedroom to follow his mom and manages to thwart the Alpha werewolf's plan. After entering the Hale property, Scott appears to save Jackson from being killed and Kate interferes. Scott gets shot and the town vet carries him back to his clinic. When he takes the bullet out of Scott's body, he reveals that he only works healing cats and dogs 90% of the time, implying that the other 10% are werewolves. Kate tells Allison the family secret and it's revealed that she's got Derek chained against the wall, torturing him.

The winter formal is coming up at the school. Kate explains about werewolves and werewolf hunters to Allison by using Derek as an example. While the vet is taking care of Scott, he is accosted by Peter, who threatens him. The vet however, refuses to give Scott to him. Peter throws furniture at the wall next to him when he is unable to approach due to mountain ash. Coach Finstock informs Scott that due to his academic standing, he won't be allowed to attend the dance. This concerns Scott and Stiles, who are aware that the Alpha werewolf is after Allison. Scott pleads with Jackson into asking Allison to the dance to protect her. When Jackson refuses, Scott shifts into a werewolf and forces Jackson to ask her, while Allison convinces Lydia to ask Stiles. They go shopping for formal clothes, where Peter approaches Allison. However, Scott's quick thinking pulls her away from him. That evening, Kate speaks to Derek, revealing that the two were in a relationship at one point but that she betrayed him. Kate figures out that Scott is the second Beta werewolf. At the dance, Jackson has gotten drunk and is reluctant to spend time with Allison. Stiles has success in wooing Lydia but she is on the lookout for Jackson. Scott also arrives and confesses to Allison that he loves her, leading to a kiss. Jackson drunkenly stumbles into the woods and sees what he thinks is a werewolf. He demands to be changed, only to see that the silhouettes are that of werewolf hunters, led by Mr. Argent. Jackson reveals Scott's identity to them. Lydia leaves to find Jackson. Stiles finds Jackson instead, who is in a confused daze. Lydia walks out to the field, where she is brutally attacked by Peter. Peter asks Stiles where Derek is, threatening to kill an unconscious Lydia. Scott and Allison go to the school buses for privacy and Allison enters a bus, beckoning Scott to come in. Before he can, Scott is blocked in between two cars, one of which is driven by Chris Argent. By the time Scott looks up, he has transformed into a werewolf, revealing his identity to a horrified Allison.

Scott, now in his werewolf form, runs away from the Argents. Chris is outraged that Kate told Allison everything beforehand and forces Kate to retreat with Allison to Washington until the Alpha werewolf is put down. Allison tries to come to terms with the fact that Scott is a werewolf. The Alpha werewolf forces Stiles to help him find Scott and Derek, revealing that Lydia - if she doesn't die - will become a werewolf. With Stiles's help, he locates the two, while Scott finds Derek. When Derek refuses to help him, Scott reveals that Peter killed the previous Alpha werewolf (Derek's sister) to become the Alpha werewolf. At the hospital where Lydia is, Jackson and Stiles are approached by Chris Argent and his team; Stiles reveals that Kate was the one who burned down the Hale household. By doing that, Kate violated the werewolf hunter's code of not killing the innocent, as there were children and humans in the house when the fire was set. Scott and Derek they are attacked by Kate and Allison, only to be stopped by Chris, who confronts Kate after realizing her true nature. He threatens to kill her if she doesn't take the gun off Scott, whom he realizes never killed anyone. Just then, Peter reveals himself and a battle ensues between Peter, Kate, Chris, Scott, Derek and Allison. Peter slits Kate's throat in revenge for burning down the Hale house, killing her. Derek is soon knocked out in the battle, leaving Scott to fight the Alpha werewolf. Jackson, Stiles and Allison help Scott defeat the Alpha werewolf. Before Scott can get the cure by killing Peter, Derek cuts Peter's throat in vengeance for his sister's death and thus becomes the new Alpha werewolf, a fact he takes to gleefully. Allison kisses Scott and says she loves him. Later, Scott and Stiles check on Lydia--she's not healing like a werewolf would, so Stiles wonders what she is now, if not a werewolf. Jackson approaches Derek and demands the bite. Derek grins maliciously and bears his fangs; it is left ambiguous as to if he really does bite Jackson.

Lydia vanishes from the hospital after a disturbing hallucination, and is found naked in the woods two days later. Isaac, a tormented teen abused by his father, is attacked while working in his father's cemetery; Derek appears to save him. Jackson begins bleeding black blood and is told by Derek that his body is resisting the bite. Derek forces Scott to watch Gerard kill an innocent werewolf and declare that they will eliminate all werewolves to avenge his daughter Kate's death.

Isaac's father is murdered by a strange creature. Scott discovers Isaac is now a werewolf. Isaac is then taken into custody for his father's murder. When it is revealed that the werewolf hunters are going to kill Isaac, Scott, Stiles and Derek plan to save him, as he is innocent. At the jail, Isaac transforms and breaks out, advancing on Stiles. Derek, being the Alpha werewolf, is able to force him into submission. Jackson, who had set up a video camera overnight to record his transformation, is upset to learn that nothing happened.

Chris begins Allison's training to become a werewolf hunter. At school, Erica, an epileptic girl, has a seizure and ends up in the hospital. There, Derek delivers the bite upon the promise that her illness will vanish. Dr. Deaton finds a dead hunter in his office and Chris wants him to find out what happened. Scott discovers Boyd is now a werewolf and is forced into a fight with Derek, Erica, and Isaac. Jackson is shocked when he exhibits inhuman strength.

When Stiles takes his jeep in for repair, he is paralyzed by the creature's toxin and witnesses it kill the mechanic. Jackson discovers there are actually over 2 hours of missing footage from the night he recorded himself. The creature attacks Derek and paralyzes him. Derek falls into the pool and Stiles jumps in to save him. They discover the creature cannot swim, so they stay in the water until Scott saves them. Derek realizes that the creature is a Kanima. Gerard reveals he knows Scott's secret and blackmails him.

Convinced that Lydia is the Kanima, since she displayed immunity to the creature's toxin, Derek wants to kill her. Scott, Allison, Stiles and Jackson try to protect her together. After a fight with Derek's pack, it is revealed to everyone that Jackson is the Kanima.

Derek engages the Kanima in a fight interrupted by Chris and Gerard. The Kanima does not attack Gerard, instead seeming to communicate with him, which confuses Chris. After the Kanima paralyzes Danny and 6 others at a gay club, Jackson passes out, so Stiles locks him up in a police van. However, Jackson transforms and escapes. Allison discovers the Kanima seeks a master, revealing that Jackson is being controlled by someone.

A fight between Scott and Jackson lands everyone involved in detention. Jackson transforms, injures Matt and Erica, and leaves a warning from his master. Erica has a seizure as a result of the Kanima's venom and Scott and Stiles rush her to Derek. Lydia meets the strange boy she has been seeing around, only for him to reveal himself to be a younger version of Peter Hale. Lydia realizes that the young boy was a part of her imagination and that Peter has been communicating with her via hallucination all along

Jackson is commanded by his master to attend a secret rave, where his next target is. Stiles and Sheriff Stilinski realize there is a pattern in the murders: all victims had been in the class of 2006. Stiles's father loses his job because Stiles's irresponsible behavior reflects badly on the county. Scott is attacked by Victoria, who attempts to kill him. Isaac drugs Jackson, and he and Erica join Stiles in interrogating his master, who speaks through him. Jackson transforms, successfully killing his target. Derek saves Scott, biting Victoria in the process.

Stiles realizes that all the murder victims were on the Beacon Hills High swim team and the coach at the time was Isaac's father. At Lydia's birthday party, Lydia spikes the punchbowl with wolfsbane petals, causing all the party attendees to hallucinate the things they fear most. She attacks Derek and brings him to the Hale house, where Peter uses Derek's blood to come back to life. Victoria kills herself so that she would not become a werewolf. It is revealed that Matt is the Kanima's master.

Matt takes Scott, Stiles, Melissa and Sheriff Stilinski hostage. Gerard persuades Allison to exact revenge on Derek for bringing her mother to suicide. Matt reveals to Scott his reason for the murders: in 2006, all the victims were at a party at Isaac's house, where Matt had come to meet Isaac. They had thrown Matt in the pool and left him to drown despite him yelling that he can't swim. Melissa finally sees Scott as a werewolf. Gerard drowns Matt in the lake and becomes the Kanima's new master.

Boyd and Erica leave Derek, terrified of the Argent werewolf genocide. At the championship lacrosse game, Gerard threatens to murder someone with the Kanima if Scott does not bring Derek to him by the game's end. Allison ruthlessly shoots Boyd with arrows until the werewolves are saved by Chris, who is upset by Allison's actions. On the field, Stiles begins a massive winning streak, and their team wins. Just then, Jackson is found bleeding and unresponsive; he has stabbed himself with his own claws. Sheriff Stilinski makes a grim discovery: Stiles has gone missing.

Stiles is kidnapped by Gerard, who also has Boyd and Erica hostage; Stiles escapes. Chris, realizing that Gerard is the true enemy, sets Boyd and Erica free, and helps Scott and Isaac take Jackson's body to Derek. Jackson turns into the Kanima, and a battle ensues. Gerard reveals he has cancer and had planned to cure himself by becoming an Alpha werewolf. However, when Gerard's body rejects the bite, Scott reveals he had replaced Gerard's cancer pills with mountain ash. Jackson is killed by Peter and Derek but comes back to life as a blue-eyed werewolf. Allison tearfully breaks up with Scott, but he assures her he'll wait. Peter reveals a pack of Alpha werewolves have come to town, indicating new danger. This Alpha pack captures Boyd and Erica as they flee.

Isaac wakes up with amnesia but is rescued from the Alpha pack by a mystery girl. Jackson has moved to London. Allison and her father have quit being werewolf hunters, and Scott is working on being a better person. Derek has been looking for Boyd and Erica, who were captured by the Alpha pack. Something eerie is causing the animals of Beacon Hills to go insane, and Dr. Deaton concludes that the animals are killing themselves intentionally. Derek gives Scott the tattoo he has been wanting to get, and explains about the Alpha pack's leader Deucalion, who is blind but the strongest and most lethal.

Stiles' childhood friend, Heather, is attacked and goes missing. The guys help Isaac recover his memory, and it is revealed that he had found Boyd and another female werewolf, being kept in an abandoned bank vault. However, Erica may already have been killed. When Derek and Scott break in to save them, Derek recognizes the other female werewolf to be his little sister Cora, previously thought dead. Stiles and Peter discover that Boyd and Cora have been kept from transforming for 3 months. Wild and bloodthirsty, Boyd and Cora almost kill Derek and Scott until Allison saves them by setting the wolves free.

Scott reveals to Allison that her mother tried to kill him, while Derek discovers Erica's body. Derek, Isaac, and Scott seek help from Chris to capture Boyd and Cora before they kill someone. Lydia finds a dead boy, and calls Stiles for help. The guys trap Boyd and Cora in the high school's boiler room but discover Jennifer is inside; Derek saves her. Stiles discovers Heather's body in the morgue, killed the same way the boy was. As the two were both virgins, Stiles concludes that someone is murdering them to offer as human sacrifices, just as Sheriff Stilinski discovers a third dead girl, killed the same way.

The body of the newest murder victim is found. The Alphas attack Derek, and Deucalion offers him a proposition: join the Alpha Pack by killing his own Betas and absorbing their power. Stiles, Lydia and Deaton figure out that the serial killer is a Darach, a dark or evil druid. Mr. Harris is murdered next, though he seemed to know the killer. Derek, aware Deucalion wants him to kill his pack, kicks Isaac out, so Isaac moves in with Scott.

The Beacon Hills cross-country team is heading to a cross-country meet aboard a bus, which Allison and Lydia are following to keep an eye on Scott. Scott is suffering from a nasty injury that isn't healing; a result of a preemptive strike on the Alphas the night before. The battle leaves everyone under the impression that Derek is dead, which Scott feels responsible for. The Alphas take a wounded Ennis to Deaton in hopes to heal him. However, Deucalion kills Ennis and absorbs his power. Allison stitches up Scott's wound, allowing him to finally heal. Back in Beacon Hills, Jennifer is startled when a wounded Derek appears and passes out.

The team takes refuge at an eerie motel for the night, where Scott and the gang undergo strange experiences. Boyd, Ethan, and Scott suffer various types of hallucinations that drive them to attempting suicide while Isaac is triggered into a PTSD flashback. All four werewolves are saved by Stiles and Lydia. Lydia realizes that the Darach caused this to happen, intending to use the wolves as sacrifices. Meanwhile, Jennifer helps heal Derek when the two have sex. Chris visits a wheelchair-bound Gerard in regards to his uncle, who committed suicide in 1977, wanting to know which Alpha had bitten him. Gerard reveals that it was Deucalion.

The Darach targets Deaton as the next sacrifice, leaving him hanging by his wrists to die. The Alpha Pack attacks Derek while Scott saves Deaton, with the help of Sheriff Stilinski. Deaton reveals Scott is a True Alpha: a werewolf who rises to Alpha status purely by their own willpower and good character. This is extremely rare, happening every 100 years, which is why Deucalion is after Scott. Kali forces Derek to kill Boyd, which also reveals Erica's death to him, and causes Derek to break down.

Seeking answers, Scott, Allison, Stiles and Cora hear stories told by two unlikely narrators (Peter and Gerard) and discover a secret about the color of a werewolf's eyes, that they change from yellow to blue when an innocent life is taken. The tale told by Peter focuses on Derek when he was a teenager. It is revealed that Derek fell in love with a girl named Paige, who he was forced to kill in order to end her suffering from a bite from an Alpha werewolf (Ennis); killing Paige darkened his soul and changed the color of his eyes. The tale told by Gerard explores the origins of the feud between the Hunters and the Packs, and it is revealed that Gerard was the one who blinded Deucalion, who was seeking peace with Gerard, during a meeting between the two sides. Also, Dr. Deaton and Ms. Morrell are revealed to be emissaries, or modern day druids, the ambassadors between the Packs and the rest of humanity.

Allison and Issac learn that the Darach is planning to sacrifice guardians next, they think that her father is involved with the murders, but end up discovering that he has been tracking the Darach for a while now. Meanwhile, Scott and Stiles want to use Lydia to solve the murders. Lydia discovers that Jennifer Blake is in fact the Darach; Jennifer is about to kill her, when Lydia screams at an extreme volume and she realizes that Lydia is actually a banshee, aka the Wailing Woman; this explains her natural attraction and inclination towards the supernatural. Stiles' dad tries to save Lydia, but is kidnapped by Jennifer, as he is a guardian. Scott goes to Ms. Morrell for some guidance; Morrell reveals that Deucalion's plan for him is that either Scott will join the Alpha Pack willingly as a True Alpha, or Deucalion will force Scott to kill, destroying his potential to become a True Alpha.

After Jennifer takes Stiles' dad, Derek and Scott capture her and bring her to the hospital in order to save Cora's life, where they are trapped by the Alphas. It is then revealed that Jennifer is in fact Kali's former emissary and that the Alphas want her dead. With the help of Peter, Allison, Chris, Stiles, and Isaac, they manage to fight against the Alphas and escape, but Jennifer kidnaps Scott's mom, since she is a guardian. Feeling that there is no other way, Scott joins Deucalion to find Jennifer, who promises to help find his mother and Stiles's father in return.

After escaping the Alphas, Derek and Peter try to find a way to save Cora, while Allison, Isaac, and Stiles discover that Jennifer has named Chris Argent as her last sacrifice, since he is also a guardian. Sacrificing himself to save Allison, Chris hands himself over to Jennifer and is taken. With the help of Lydia's drawing and Deaton, they discover that Jennifer is holding her victims in the root cellar. Stiles and Lydia finally have their first kiss when Lydia kisses him to help him get through a panic attack. Scott and the Alpha pack hunt down Ms. Morrell; Deucalion injures her with the blade in his cane. Morrell tells Scott that he needs to find the Nemeton. Stiles and Lydia discover that the tree drawings Lydia has been making all season are actually upside-down renderings of the Nemeton's root cellar. Peter tells Derek that as an Alpha, he can heal one of his own, even at the brink of death, but at the cost of his status as an Alpha. Choosing family over power, Derek heals Cora, losing his Alpha powers in the process. Stiles and Deaton find Scott and convince him that they need to be 'temporarily' dead in order to find out where their parents are. Scott, Allison, and Stiles are then put into tubs of ice (by Deaton, Isaac and Lydia, respectively) and pushed down. It is also revealed that Scott's dad, an FBI agent, is in town.

Scott, Allison, and Stiles awaken and discover where the Nemeton is located. Jennifer kills Kali and badly wounds the twins. Allison, Isaac, and Stiles locate the Nemeton and rescue the three parents. Deucalion and Scott fight against Jennifer and Derek in the distillery; Deucalion reveals his true power and easily takes down Jennifer and Derek, but then tries to force Scott to kill Jennifer. Scott refuses and uses a flashbulb arrow to temporarily blind Deucalion, taking advantage of his possessing sight in his transformed state. The lunar eclipse begins, and all the werewolves become powerless. Jennifer gives Deucalion his sight back so he can see her true form and then tries to kill him, but is stopped by Derek, who reveals that the effort of healing Deucalion's eyes has weakened her. Jennifer attacks Derek, but the eclipse ends and the werewolves' power returns. Scott defeats Jennifer and becomes a True Alpha. Deucalion slashes Jennifer's throat, apparently killing her. Deaton, Lydia and Cora manage to save the injured twins. Deucalion is allowed to leave town; Derek and Cora leave Beacon Hills; Allison and Chris renew their code as hunters; Scott and Stiles return to their normal lives. Jennifer is revealed to be barely alive, having survived Deucalion's attack; she makes her way to the Nemeton, but is confronted by Peter. Jennifer suggests that Peter will want to kill Scott, in order to steal his power and became an Alpha again. Peter then kills her, claiming that he has always been the Alpha.

As a result of their temporary deaths, Scott, Stiles, and Allison are now experiencing vivid hallucinations. Allison is haunted by visions of Kate, her dead aunt; Stiles has terrible nightmares and is unable to read even when awake; and Scott has begun to see his shadow as that of an Alpha werewolf. Deaton explains the hallucinations are a result of an open door in their minds, which they must find a way to close. Sheriff Stilinski has reopened an 8-year-old case after learning of the supernatural world, as he believes the death of a family was the result of a werewolf attack. Scott's FBI agent father will eventually take over Sheriff Stilinski's cases. Scott and Stiles search the crime scene of the reopened case for clues, finding a coyote whose eyes glow blue. Scott believes the coyote is one of the family members presumed dead, a girl named Malia. Derek and Peter have been kidnapped and are being tortured by an unknown organization.

Scott and his friends attempt to track down the were-coyote Malia before her father kills her, in order to change her back to a human. Isaac becomes caught in a coyote trap while Stiles saves Lydia from another. Allison uses a tranquillizer dart to sedate Malia's father. Scott tracks down Malia and embraces his Alpha powers in order to transform Malia back into a human. Sheriff Stilinski then reunites Malia with her father. Meanwhile, Peter and Derek are freed from their captors by an unlikely ally, Braeden, who reveals that she was hired to free them by Deucalion. At the Nemeton, someone releases a swarm of fireflies who morph into three mysterious figures.

William Barrow, an electrical engineer turned mass murderer, escapes during surgery and hides out in the school. He abducts Kira and attempts to electrocute her, but she inexplicably deflects the electricity, killing him and shutting down the power for the entire town. Just after the blackout, five hooded figures attack Isaac.

Isaac describes the hooded figures that attacked him to Allison and her father. It is revealed that Allison's father is keeping a mask identical to the ones worn by the hooded figures in the apartment. Kira reveals to Scott that her body emanates a glowing aura when a photo is taken of her, and with the help of Stiles, the two break into the Sheriff's office and erase similar photos from Kira's confiscated cell phone. Derek is attacked by the hooded figures. Danny and Ethan throw a Halloween party in Derek's empty loft. During the party, Scott realizes that Kira's aura resembles a fox, and Allison discovers what appears to be a reverse number 5 mark behind Isaac's ear. Ethan and Lydia are also attacked by the hooded figures and marked the same way. Scott and Derek fight the hooded figures once the party is shut down, however, they attack and mark Aiden. Elsewhere, Allison's father collapses after an unknown brutal attack. Stiles, who finds a mysterious key on his key chain, discovers that it opens the door to the room at the school in which Barrow had hidden. There, he discovers that his handwriting matches the coded message written on the chalk-board, instructing Barrow to kill Kira.

Allison's father recounts his time in Japan when he was eighteen; he and members of the Japanese yakuza encountered the hooded figures, which are revealed to be called Oni; he explains that they killed the entire gang, but that their target was the leader, who was some kind of supernatural creature. He, Allison and Isaac plan to infiltrate the lair of the only other survivor, a man called Katashi (nicknamed Silverfinger after his unusual prosthetic) in order to gain answers. Worrying about his sanity, Stiles seeks help from Melissa, who sedates him so that he'll be forced to get some rest. She discovers that his symptoms are identical to those of his deceased mother, Claudia. Scott, Kira, Derek, the twins, Melissa, and Agent McCall take sanctuary in Scott's home just before the Oni attack. The Oni are forced out of the house, but not before Scott's father is seriously wounded. Katashi, the surviving member of the yakuza, informs Allison and her father that the Oni seek a dark spirit, an evil kitsune known as a Nogitsune, and will not harm supernatural beings that are innocent, whom they mark with the Japanese kanji for self (?). Katashi also warns Chris to let the Oni destroy the Nogitsune, regardless of who it has possessed. The Oni breach Scott's house, but do not harm him or Kira. Back at the hospital, Stiles awakens and is confronted by the Oni, who attempt to test him for possession. Before they can perform the test, Stiles destroys one of them. Scott finds Stiles, who acts as if nothing happened, suggesting that Stiles may be the dark spirit the Oni seek.

Stiles makes a panicked late-night phone call to Scott after he finds himself in a strange location with his leg in a steel trap. A mysterious figure speaks to him in Japanese and asks him riddles. Scott, Isaac, Lydia and Aiden attempt to find him. Lydia leads them to the mental health center where Barrow was committed, however Stiles is not there. Scott's mother and father find Stiles, who had been sleepwalking. Allison receives multiple voice mails in Japanese from an unknown number. She and Isaac ask Kira's father for help in translating the message; he says that the voice is reciting emergency protocols for a Japanese internment camp during World War II, but that the camp the voice is referring to (named Oak Creek) never existed. Derek and Kira find Stiles's baseball bat at the power station, and Derek deduces that Kira was indirectly responsible for the Nogitsune (dark spirit) taking over Stiles's body. Stiles has an MRI scan to test for frontotemporal dementia, the same illness that caused his mother's death. During the MRI scan, which shows that Stiles does indeed have the disease, the mysterious figure reappears in Stiles's mind and threatens Stiles and his loved ones. The figure removes the bandages covering its head, revealing that it looks exactly like Stiles. The power then goes out, due to the Nogitsune having damaged the wiring on the roof the previous night. The Nogitsune, now in complete control of Stiles's body, confronts the remaining Oni, who are revealed to be led by Kira's mother.

Deaton retrieves a poisonous plant that will aid him in defeating the Nogitsune. Meanwhile at the hospital, an electrical wire swings out of control and injures several people, including Isaac, before Kira uses her powers to subdue it. Elsewhere, Derek and Chris Argent are arrested by Agent McCall for the murder of Katashi aka Silverfinger after being framed by someone. Stiles, who is still missing, reappears in the school basement. After finding a map of the cross-country trails, he, Scott, Aiden and Ethan realize that the path has been booby trapped by the possessed Stiles. The boys are successful in stopping the runners from being injured but Coach Finstock is shot with an arrow. A gift wrapped present - similar to the one left in Coach Finstock's office - is found on one of the school buses and thought to contain a bomb. The box is revealed not to contain a bomb but Sheriff Stilinkski's name plaque from his desk; the bomb's true location. The bomb explodes injuring and killing officers. Whilst this is happening, Allison and Lydia seek the aid of an unlikely ally; Peter Hale. In return, he asks for Lydia's help in finding out the memory that his sister took away from him several years ago. Lydia discovers that Peter is not only an uncle but also a father. She later reveals to Allison that she thinks his daughter is Malia Tate. The Oni, who have been summoned by Kira's mother via sacrificing her Kitsune tails, attack Stiles, Scott and Kira at the vet's office. They manage to escape but Stiles - still possessed by the Nogitsune - knocks Kira unconscious, revealing that he was deceiving Scott all along. Before Stiles can do any further damage, Deaton appears and subdues him.

Stiles checks himself into Eichen House, a mental hospital. Shortly after his arrival, another patient commits suicide and he meets his roommate, Oliver. It's revealed that Chris Argent (who is still in jail with Derek) and Deaton were working together, and the letharia vulpina lichen will only work on Stiles temporarily. Deaton requires a hidden scroll in his quest to cure Stiles. In the mental hospital, Stiles encounters Malia Tate, who isn't pleased to be reunited. After group therapy with Ms. Morrell - the school guidance counselor and aid to Deaton - Stiles is told that he must stay awake if he wants to prevent the Nogitsune from taking over again. Stiles enlists Malia in a plan to access the basement, but after she steals the keys for him, he is caught, locked in solitary confinement and sedated. Scott, Allison, Lydia, Aiden, Ethan and Kira hatch a plan that will retrieve the scroll from an armored vehicle only for it to go awry when Kinkade - another werewolf - tries to take the scroll for himself. Chris meets with another hunter - Araya, the leader of the group who tortured Derek and Peter - who tells him how disappointed she is with his work. Malia rescues Stiles and the two head to the basement together, where they share a passionate encounter. Soon after, Malia realizes that the wall with the kanji carved into it is hollow, and the Nogitsune lies behind it, but the two are subdued by Oliver before they can react. The group struggle in their fight with Kinkade, but manage to overpower him. The Nogitsune gives Stiles an ultimatum; allow it in or watch Malia die. He chooses the former, and allows the Nogitsune to possess him again. Deaton reads the scroll and says that the Nogitsune's host body needs to change its form in order to remove it, meaning that Stiles needs to become a werewolf. Malia leaves the mental hospital in search of Scott.

After receiving an old war photo from Malia, Kira learns that her mother is actually a Kitsune who is close to 900 years old. During the second world war, she was in a Japanese internment camp, and fell in love with a young medic. The doctor at the internment camp was selling medicine on the black market that was badly needed by the Japanese, as they were dying of pneumonia. A riot breaks out, and the young medic is badly burned by a molotov cocktail thrown by an old Japanese woman, Satomi, who is a werewolf. Noshiko is shot many times by the MPs, and the young medic dies in Eichen House in pain, as the doctor sold the morphine as well. Noshiko, assumed to be dead but actually healing and unable to move, calls upon a Nogitsune to posess her so that she can have her revenge, but the Nogitsune posesses her lover's body instead. The Nogitsune goes on a killing spree, killing all of the staff and residents of Eichen House, as well as the Japanese and MPs at the internment camp. Noshiko, fully healed and knowing that as a kitsune, she is the only one that can stop the Nogitsune, gets a katana that she had hidden, and, with the help of Satomi, is able to stab the Nogitsune. The Nogitsune is defeated and exorcised from its host body, but the sword shatters into pieces. The Nogitsune leaves the body of her lover, in the form of a fly. Kira, as a Thunder Kitsune, is able to mend the katana, and her mother gives it to her to stop the Nogitsune once again. Noshiko reveals that she hid a glass jar containing the Nogitsune in the roots of the nemeton, meaning that Scott and his friends may have been partially responsible for the reawakening of the Nogitsune with their sacrifice for their parents. Meanwhile, Derek, Chris, Allison and Sheriff Stilinski try to track down Stiles, hoping to bring him back to normal.

Sheriff Stilinski faces a review board, but Scott's father saves his job at the last minute. Mr. McCall reveals to Sheriff Stilinski that he only came back to Beacon Hills to make amends with his son. Meanwhile, the Nogitsune stabs himself and releases a swarm of flies, sending them to go after Aiden, Ethan, Isaac and Derek. Having been placed under the spell of the Nogitsune by the flies, Derek tries to get revenge over Chris, by covering him in gasoline and attempting to burn him; however Chris is able to free himself and knocks out Derek. Aiden, Ethan, and Isaac nearly kill each other but are saved by Kira and Allison. Scott, Lydia and Peter join forces to remove the Nogitsune from Stiles. With guidance from Peter, Scott and Lydia are able to enter Stiles's mind, and manage to free Stiles from the Nogitsune's control, expelling the Nogitsune from Stiles's body. However, during the confusion, Lydia is kidnapped by the Nogitsune, which is now an independent being and looks exactly like Stiles.

While searching for Lydia in the woods, Aiden and Ethan are shot at by an unknown shooter with wolfsbane bullets, and are saved by Derek. Kira's mother tries to teach her the board game that Stiles was playing with the Nogitsune. Later, Kira's father discovers that the Nogitsune and Kira's mother play the game the same way, which makes Kira suspicious. Lydia is taken to the internment camp by the Nogitsune; the group arrive there and find Kira's mother and the Oni, who plans to kill the Nogitsune, even if it means killing Stiles. The Nogitsune takes possession over the Oni and has them face off against Kira, Allison, and Isaac, while Scott and Stiles find Lydia and are shocked when she asks why they came when she told them not to. Allison manages to kill one of the Oni and is stabbed by another while caught off guard. Allison professes her love to Scott and dies in his arms.

With the Nogitsune in control of the Oni, there is little time to grieve the loss of Allison, as Scott and Derek call upon their friends and allies to make a final stand. The Oni, under the control of the Nogitsune, systematically and violently take control of the hospital, Sheriff's station, high school and Alan's animal clinic. Meanwhile, Isaac and Mr. Argent realize that silver can actually poison the Oni and destroy them. Everyone attacked shows signs of the poisoning seen in others attacked by the Oni. But Scott, Kira, Stiles and Lydia defeat the Nogitsune at the school by realizing the attacks are merely a powerful illusion, and they are able to escape. Meanwhile, Derek, Ethan and Aiden fight the Oni. They are just about to give up hope when Argent and Isaac show up and destroy the Oni with the four other silver arrows created by Allison. While Aiden is attempting to kill one of the Oni, he is stabbed and dies in the arms of Ethan. Scott bites the Nogitsune, following the instructions on the scroll stating that it cannot be both a fox and a wolf. Kira stabs the Nogitsune with her katana, exorcising it from Stiles once and for all. The duplicate of Stiles that the Nogitsune was using as a body disintegrates, and Isaac traps the Nogitsune (which took the form of a fly) in a box made of Nemeton wood. Later, the injured people start healing and all seems well again in Beacon Hills. Scott begins trying to teach Malia how to control her abilities. Ethan tells Danny that he can't stay anymore and also discovers Danny knew about werewolves and the supernatural activities. Derek is shown talking to Stiles about a dream, but later realizes that it was real. In a series of flashbacks, it is revealed that a wolf scratch can cause someone to 'turn' if the nails go deep enough. Kate Argent, whose throat was torn out by wolf claws, is shown to be alive and is a supernatural being (the La Loba that the Mexican hunters were searching for).

Stiles and Lydia head into Mexico, looking for the Spanish hunters (known as the Calaveras) that were hunting Derek. When paying them off fails, Scott, Kira, and Malia take down their enforcers, only to be defeated by the hunters using smoke mixed with Wolfsbane. The lead hunter, Araya, questions Lydia about her Banshee powers and Scott's True Alpha status before brutally interrogating Scott herself. Araya reveals someone attacked her hunters and captured Derek and through a vision via electro-shock, Scott learns that the person responsible is Kate Argent, Alison's formerly dead aunt. Lead by Braeden, Scott tells Malia and Kira about Kate's role in the Hale fire and deduces that Peter's attack must have allowed her to survive. The Calaveras switched her body out of the morgue before her burial, suspecting that she was turning. When Kate's body healed itself, they instructed her to commit suicide, as per the hunters' code; however, Kate faked her own suicide, and then killed her guards and escaped. After Stiles's Jeep suffers a mysterious breakdown, Scott is forced to leave with Braeden to an ancient church honoring creatures known as the Nagual (werejaguars), where they expect to find Derek. Malia finds a mysterious bone knife in the Jeep's engine. Both groups suddenly come under attack by mysterious creatures wearing bone armor; Malia and Kira chase off one, while Scott uses his Alpha roar to scare off the other. Scott and Braeden find a teenage version of Derek buried in the church.

The opening scene shows young Peter teaching young Derek to learn to control his werewolf abilities, using an artifact known as the Triskelion. In the present day, Kate brutally kills a gas station attendant, and appears to be unable to control herself when transformed. Scott and his friends, who have returned from Mexico, take Derek to Deaton, who is baffled by Derek's regression. Lydia stays with Derek overnight while Scott and Stiles return home. In the morning, Deaton finds out that Derek is healing in an unusual manner - he heals much more rapidly than usual, and he has a high fever. Later, as they begin another experiment, Derek awakens, but is disoriented and confused. He attacks Deaton and disappears. He is later found by two sheriff deputies near his destroyed house. Scott teams up with an unlikely source - Peter - in the hopes of putting an end to Kate's evil plan, which involves using Derek to get into the Hales' family vault (under the high school) and find the Triskelion in order to learn control over her shift. Scott, Peter, Malia and Kira re-encounter the creatures that attacked them in Mexico, which Peter identifies as Berserkers. Scott, Kira and Malia fight the two Berserkers, but are easily defeated. Peter confronts Kate and Derek in the vault, where he explains that the Triskelion was just a trinket for Derek to focus on; Derek learned control by focusing on his anger. Derek goes to help Scott and the others, and engages the Berserkers in combat. Peter faces off against Kate, but they are interrupted as an unknown individual blinds them using flash grenades. Kate flees, and the new arrival steals a briefcase from the vault and leaves while Peter is blinded. The Berserkers run away when Kate calls them, and Derek reverts to his normal age, but with yellow eyes. Stiles and Lydia find Peter alone in the vault; he explains that the whole thing was a heist, and that $117 million worth of bearer bonds were stolen from the vault.

A young boy searches for his cat, only to find it covered in blood under his bed. The boy, Sean, escapes from his attacker, a man with no mouth who just murdered his family. Derek and Peter hire Braeden to track down Kate to retrieve their stolen bearer bonds and learn the reason why Derek's eyes are yellow. Stiles and Scott discuss the theft at Lacrosse practice, where they see a new freshman, Liam (Dylan Sprayberry), excelling on the field. Kira learns her parents are planning to move back to New York, which she disapproves of, and Stiles and Lydia help Malia to improve her math skills. Scott's mom and Sheriff Stilinski learns of Sean's attack and decide to keep the kids out of it because it didn't have supernatural elements. When Coach Finstock said the team is going for a 'rebuilding' season, Stiles and Scott struggle to maintain their positions, while Liam begins dominating. Scott finally uses his werewolf skills at Stiles's prompting, and they begin to excel, but Scott accidentally injures Liam. Meanwhile, Coach discovers that Kira has a talent for Lacrosse herself. After practice, Scott and Kira reaffirm their relationship, before he leaves with Liam for the hospital. Deputy Parrish and Lydia investigate Sean's house, where they find a hidden meat locker full of frozen human corpses. Sean, identified as a Wendigo, kills and devours one of the cops protecting him and proceeds to attack Scott's mom, but Scott arrives and saves her. Sean takes Liam hostage, and Scott tracks them to the roof. Liam breaks free and falls over the edge, but clings to the edge of the roof. Scott is restrained by Sean, and is forced to bite Liam's arm to keep him from falling. The man with no mouth kills Sean and lets Scott live, only to face the reality that Scott's bite may have turned Liam into a werewolf.

In the events of the last episode, Derek and Sheriff Stilinski examine the Wendigo's body after the Mute's attack. Scott and Stiles take Liam back to his house, but he escapes before they can fill him in on what he saw. Meanwhile, Peter is attacked by the Mute. The next day, Malia and Stiles prepare for the full moon and Lydia and Kira try to decipher the computer code that Lydia wrote down in Malia's math notes. Liam soon starts exhibiting his werewolf powers and Scott and Stiles unsuccessfully try to gain his trust. Without Liam's trust, Lydia suggests that they trick Liam into getting him to Lydia's lakehouse and Kira manages to convince him to go with her. Derek painfully fixes Peter's wound, and Peter shows him a glove he got off the Mute during the fight. At the lakehouse, Stiles learns that Liam was kicked out of his previous school after a violent attack on a teacher's car. Derek brings the glove to Stilinski, and Deputy Parrish identifies both the glove and the Mute's tomahawk as military equipment. Liam is brought to the lakehouse and is brought up to speed on the supernatural, but both he and Malia begin to lose control. Worse still, Liam texted his friends and others that there was a party there, and dozens of students show up at the lake house. As Lydia distracts the guests, Stiles hides Malia in the basement, and Scott and Kira chain up Liam in the boat house. Parrish, Stilinski and Derek discover that the Mute is an assassin hired by someone called the Benefactor. At the party, the guy that delivered the keg, DeMarco Montana, is revealed to be a werewolf, and is killed by Violet, one of Liam's friends; it is revealed that she and Garrett are also agents of the Benefactor. Kira teases Scott about his self-control on a full moon; Liam then loses control, breaks free of the chains and escapes. Malia struggles with her restraints, but Stiles, using his experience with the Nogitsune, helps her gain control over her transformation. Derek and Stilinski find the Mute at the school and foil a trap that he had laid for them using a claymore explosive; the Mute then attacks them directly. Derek is able to overpower him, but Peter intervenes and kills the Mute. Scott finds Liam in the forest and, thanks to Chris Argent's arrival, he is able to capture Liam. Liam reveals his fear that his parents will look at him as a monster, like after his attack on the teacher's car. Scott assures him that he is a werewolf like Liam and comforts him. Lydia manages to decipher the code, using the keyword ALLISON; she and Kira discover that the code is actually a deadpool, a hit list of supernatural beings living in Beacon Hills, which includes all of their supernatural friends.

Violet stalks an injured werewolf at school; the werewolf, Carrie Hudson, manages to overpower Violet and escape, but is then killed by Garrett. Scott and Stiles explain the Deadpool to Sheriff Stilinski and that the information Lydia decoded was only part of the list. They guess that the $117 million that was stolen from the Hale vault is being used to finance the assassins, and realize that the werewolf that was killed at the party was lured there, meaning that his killer is a student. Liam learns that their first lacrosse game is against his old high school, and Derek tests Liam's strength in the locker room. Scott calms him down and Derek remarks that Scott will be good at training him, even though Scott admits he is not ready. Malia tries to help Lydia use her powers to find the next cipher key; when Lydia is unsuccessful, they decide to find Meredith Walker, the Banshee that escaped from Eichen House. Stiles discovers from the latest victims crime scene photos that the killer is on the Lacrosse team. Violet and Garrett makes preparations to capture a Beta werewolf using a rare species of wolfsbane, but she argues they should go after Scott. Garrett reminds her that Scott went up against the Alpha Pack and won, meaning that, that despite the money, he is too dangerous to go after. Lydia becomes frustrated by her lack of control and argues with Malia that her power isn't like hers that can turn on and off. Liam tries to make amends with his former team, but they bully him for what he did to his coach's car. Scott and Stiles manage to get him away before he wolfs out. After calming him down again, Liam confesses he has Intermittent Explosive Disorder which explains his poor control over his anger. Scott tells Liam about the killer, and Liam remembers that Garrett paid for the beer keg that lured DeMarco there. Derek shows Argent the Hale vault and explains that since he reverted from a teenager, he has been losing his powers. Scott, Kira and Stiles struggle to keep Liam under control during the lacrosse game as his old team keeps targeting him. Meredith shows up at the police station, saying that Lydia called her, and gives Lydia and Malia a clue to the next part of the Deadpool, which Lydia uses to spell out the keyword AIDEN. Stiles relays the next part to the others, and they learn that Brett, a werewolf on Liam's old team, is on the list. Garrett cuts Brett with a blade containing the rare species of wolfsbane, and Violet attacks him in the locker room. Scott finds Brett alive and is attacked by Violet, but Scott effortlessly overpowers her. Deputy Parrish offers to drive Lydia home, but she declines and seems alarmed. The computer's screen is shown, revealing that Parrish's name is also on the list. Chris is confronted by Araya and Severo from the Calaveras hunters; Araya tells him that Braeden hasn't checked in, and suggests that they rely on each other rather than outside sources. Araya plays on Chris' grief over his wife and Allison's deaths and has him repeat the old Hunter's Code; We hunt those who hunt us.

Four weeks earlier, Kate receives a mysterious message regarding the Triskelion on a mix tape. In the present day, she and the two Berserkers kill a group of assassins working for the Benefactor; one of the assassins tells her that there was another tape, received by someone called the Orphans. At the high school, Violet is taken into custody by the police; in the process, Agent McCall recognizes her as a member of the Orphans, who are revealed to be a group of teenage serial killers. With help from Derek, Stiles and Peter, Deaton manages to purge the wolfsbane toxin from Brett's system, allowing him to heal. When they overhear Brett muttering an odd mantra - The sun, the moon, the truth - Derek realizes that DeMarco, Carrie Hudson, and Brett are all members of another werewolf pack, let by Satomi, one of the oldest werewolves still living, and the one who helped Kira's mother to defeat the Nogitsune during World War II. Derek enlists Malia to help him track down Satomi's pack, only to realize that they are hiding and concealing their scents. Meanwhile, Stiles and Lydia inform Parrish that his name is on the Deadpool, although they do not tell him what it means. Garrett attacks Liam in the woods, stabs him with the wolfsbane-poisoned blade and throws him into a well, before using him as a hostage to convince Scott to help him free Violet from police custody. Stiles, Lydia and Parrish return to Eichen House in search of Meredith, hopeful that she can help Lydia to discover the final code word. However, Meredith refuses, saying that the Benefactor has ordered her not to help them anymore. When Stiles and Lydia continue trying to persuade her, she suffers a breakdown and screams so loudly that Lydia's ears start to bleed. Scott and Garrett find the car in which Agent McCall and Sheriff Stilinski were transporting Violet; unfortunately, Kate and the Berserkers have already intercepted the car and taken Violet. One of the Berserkers kills Garrett, and the other knocks Scott unconscious before leaving. Deaton and Chris are able to heal Scott; Scott and Chris then go after Kate, hoping that Violet knows where Liam is being held. Elsewhere, Derek and Malia finally locate Satomi's pack, only to find that they are all dead, apparently from poison. Derek also finds Braeden badly injured among the bodies. Scott and Chris face off against Kate and the Berserkers, but are easily overpowered. During the fight, Scott discovers that Violet has already been killed. Kate calls off the Berserkers, not allowing them to kill Chris. Liam, who is still trying to climb out of the well, manages to channel his anger and howls, enabling Scott to find and rescue him. Stiles and Lydia theorize that, since the other two keywords were the names of people who have already died, perhaps the last keyword might be the name of someone who has not died yet, but will. Lydia uses her banshee abilities and starts pressing keys on the computer keyboard with her eyes closed, spelling out the final keyword: DEREK. The remaining third of the list is uncovered; it includes Satomi, Malia, Liam and Meredith. Fearing that Meredith may be in danger, Stiles and Lydia call Parrish, who gravely informs them that Meredith is already dead; she committed suicide by hanging herself and Stiles comforts Lydia. Scott decides that he will not condone any more deaths, and states that he will save everyone else on the list, no matter what supernatural creature they happen to be. Scott and Stiles open a bag that was in Garrett's locker, containing all of the money that Garrett and Violet received from the Benefactor, and discover another mix tape among the money. Peter confronts Kate in the sewers, and offers her a deal; he will teach her how to control her shift, if she helps him to regain his stolen money and power.

A man in a lab coat is slowly killing a werewolf through unknown means while listening to a tape sent by the Benefactor. At the same time, Scott and Stiles are listening to the same tape and discuss the money they found in Garrett's locker. While Scott wishes to return the money to Derek, Stiles reluctant to because the money also belongs to Peter. Malia arrives to tell them the pack she and Derek were searching for in the last episode are all dead and Derek rushes a mortally wounded Braeden to the hospital. Deaton soon encounters Satomi, the Alpha of the dead pack, outside of the clinic. The next day, Scott, Stiles, Malia and Kira are at the school taking a PSAT (Preliminary Scholastic Aptitude Test), but unknown to them is that the man in the lab coat, simply called the Chemist, is supervising the test. When a student almost collapses, Lydia's mom, who is also supervising, notices red welts on her arm and she discovers that an unconscious Coach Finstock has the same welts. Realizing the gravity of the problem, she calls the Centre for Disease Control to quarantine the school, trapping all of them inside. Deaton exams one of Satomi's sick betas and explains they were in the woods when more of her pack got sick. Melissa wakes Braeden up, who informs both her and Derek that it wasn't poison that killed Satomi's pack, but a virus specifically designed to kill werewolves. Lydia, meanwhile, is at the lakehouse, trying to communicate with the deceased Meredith Walker, but finds a photo of her in the lakehouse. Back at the school, Scott and Malia begin to feel the virus's effects and it's also affects Kira and Stiles in a different way. Fearing the virus could make them go wild, Stiles says they need to hide in the Hale Vault and deduces a second way inside. Stiles and Scott convince Malia to open it, without telling her that only the Hales can open it and lock themselves inside. Melissa and Derek try to help Satomi's beta at the hospital, but dies before they could treat him. In the vault, Scott and Stiles argues about telling her about her parentage to Peter. Stiles points out Peters past actions and the fact his name is not on the Deadpool, suspecting he could be the Benefactor. He also fears that if they do tell Malia, they will lose her to him. Lydia gets to the school and when asked by Sheriff Stilinski, she is certain someone inside is going to die. Deaton figures out that the virus is a weaponized version of Canine Distemper, a deadly disease to wolves. Thanks to a chance comment by Satomi, Deaton learns that the Reishi tea leaves is the cure to the virus and Derek says there is more in the vault. Forced to leave the others to avoid suspicion, Stiles finds that the ink used to fingerprint the students for the tests is coated with the virus and the Chemist threatens him at gunpoint. Agent McCall saves him by shooting the Chemist and relays information from Melissa to Stiles, without knowing what it means. Another assassin attacks Derek and Satomi in the hospital only for Satomi to kill the assassin after dodging point-blank gunfire. Stiles rushes back to tell the others, but the virus has rendered them all blind. Using the last of his strength, Scott uses his enhanced vision to find the tea leaves and breaks the jar, releasing the spores; which cures the virus. Now cured, Malia silently walks away from the others after seeing her name on the Deadpool as Malia Hale.

Kira, Liam, Scott and Stiles start working on their plan to lure out the Benefactor - Scott is put into a near-death state by Kira, brought in to the hospital, and declared dead, and his friends have 45 minutes before he dies permanently. Derek reveals to Braeden that he has now lost all of his powers; Braeden teaches him how to use guns and fight without his supernatural abilities, which leads to a passionate encounter between them. Scott experiences repeated hallucinations in which Liam urges him to embrace his werewolf nature, and tries to convince him that he can kill the assassins. In the first two hallucinations, Liam fails to convince Scott, and is then killed by the Mute; in the third, Scott ultimately kills Liam with the Mute's tomahawk. A confused Malia seeks out Peter to get information about her family, especially her biological mother; Peter says that he is trying to locate her mother, who is known as "the Desert Wolf", but needs her help. Kate and the Berserkers break into the hospital in an attempt to confirm whether Scott is dead, but Chris is able to persuade her to leave; however, Kira's mother is injured by one of the Berserkers. Lydia discovers important information about her "deceased" grandmother that suggests her grandmother was also a banshee. Scott and Kira realize that the Benefactor might be a banshee. Lydia discovers that her grandmother wrote down part of the deadpool code, finds another message in the same code, and questions if her grandmother is truly dead.

Deputy Parrish is attacked and burned alive by his partner, only to survive completely unscathed, which brings him into the supernatural world. Scott, Derek, Lydia and Parrish realize that the deadpool is available to anyone with access to it. Lydia explains her grandmother's history; after predicting the death of her girlfriend, Lorraine spent many years researching numerous different subjects in an attempt to learn how her powers worked. One of her subjects was Meredith, but the tests seriously injured Meredith, forcing her to spend a year in a hospital; she never fully recovered. Realizing that her grandmother could be the key to identifying the Benefactor, Stiles and Lydia figure out that the coded message written by Lydia's grandmother was another list of names, including Lydia's grandmother; with help from Parrish, they realize that all of the names on the list belonged to deceased patients at Eichen House who committed suicide. Stiles and Lydia go to Eichen House to look through the files, but are attacked by Brunski, the head orderly, who is presumed to be the Benefactor. Scott, Liam and Malia attend the annual lacrosse bonfire, but it turns out to be a trap; the music distorts their senses and makes them sick, allowing the guards (who were working with Parrish's partner) to ambush them. Derek and Braeden rescue them, and Parrish saves Stiles and Lydia from Brunski, having realized that he pronounced all of the patients on the list dead. Parrish shoots Brunski, killing him, only for Lydia to realize that he was not the Benefactor. Meredith Walker enters the room, still alive, and reveals that she is the Benefactor.

Kira saves Brett Talbot and another werewolf named Lori from a team of hunters who are after them due to their prices on the Deadpool. Scott races to the Clinic, reunites with Kira and meets Satomi and her pack. Stiles and Malia reconcile and discovers that the tape left by Lydia's grandmother was made at the boathouse. Meanwhile, Lydia tries to get Meredith to talk, but Meredith says that she will only talk to Peter Hale. After realizing that Meredith knew him while he was comatose, Peter uses the werewolf ability to read minds in order to find out how she knows him. Lydia discovers that during her stay in the hospital, Meredith was placed in the same room as Peter. She involuntarily listened to Peter's thoughts, particularly a mad raving where he plotted to hire the assassins of the Deadpool to kill off the supernaturals of Beacon Hills and create a stronger breed in his image, and was influenced by those thoughts. When Meredith heard Lydia's scream at the moment when Allison was killed by the Oni, she decided to carry out Peter's plan; she used Brunski to steal Peter's money from the Hale vault, and hired the assassins to eliminate every supernatural creature in Beacon Hills except Peter. The hunters track down Satomi's pack and Braeden, Chris, Derek, Kira and Scott fight them off. During the fight, Scott further transforms into a new form during a frenzy, but is able to regain control when the hunter he was fighting surrenders. Stiles and Malia discover a room filled with old computer servers behind the wall of the soundproof study at the lake house, which house the deadpool. Thanks to Lydia's instructions, they are able to shut down the computers, deactivating the deadpool and terminating all of the Benefactor's contracts. With their contracts terminated, the remaining hunters withdraw. Peter meets with Kate and, despite being rattled by his encounter with Meredith, continues with his plan to kill Scott and steal his Alpha powers.

Dr. Deaton captures Patrick, a wendigo who escaped from Eichen House, and returns him to a secret area of the hospital housing various supernatural creatures. He meets with one of the inmates, a three-eyed man named Dr. Valack, who claims to have knowledge regarding what Kate did to Derek. Deaton obtains the information by looking into Valack's third eye, but is sent into a coma as a result. Meanwhile, Liam is suffering from nightmares and hallucinations of the Berserkers. Lydia appears at Derek's loft in the middle of the night and screams. Chris tracks down Kate in the sewers, but encounters Peter and one of the Berserkers instead. Peter impales Chris with a metal bar, pinning him to a wall, and leaves. As Stiles and Liam prepare for the first lacrosse game of the season, Scott and Kira go on their first official date in Derek's loft, but are ambushed by Kate and the other Berserker. Scott and Kira put up a good fight, but are eventually defeated and abducted. Lydia is able to awaken Deaton from his coma; he informs the group that Scott and Kira have been abducted, and that Kate has taken them to Mexico. Peter shows up at the lacrosse game to see Malia, informs her that he has found her mother, and offers her a deal; he will give Malia her mother's identity if she helps him to kill Kate. During the game, Brett helps Liam to learn control over his fear, as part of Brett's debt to Scott for saving his pack. Deputy Parrish finds Chris in the sewers; working together, they are able to free Chris. In the process, Parrish's eyes glow orange. Kate imprisons Scott and Kira in the abandoned church in La Iglesia (the abandoned town in Mexico where she was keeping Derek at the beginning of the season), and informs Scott that she is planning to turn him into a Berserker to use him against his friends.

Kira awakens in the tunnels beneath La Iglesia; Scott, who has been fully converted into a Berserker, attacks her and stabs her with a bone knife on Kate's orders. Kate explains that she was instinctively drawn to La Iglesia after she turned into a Nagual, and found the first two Berserkers waiting for her; with help from Peter, she realized that she could also create her own. Stiles, Derek, Malia, Liam, Braeden and Peter set out for La Iglesia. Lydia and Mason are attacked by one of the Berserkers at the school, and are held prisoner in the basement; Lydia realizes that Kate wants to make sure that she cannot help the others. Liam begins to lose control due to the full moon, but Stiles and Derek are able to help him regain control of himself by having him recite Satomi's mantra. With the help of a hallucination of Noshiko, Kira is able to trigger her supernatural healing ability. The pack arrive at La Iglesia, but are immediately attacked by the Berserker-transformed Scott. Derek is badly injured, and Braeden stays behind to protect him while Stiles, Peter, Malia and Liam pursue Scott into the church. Stiles finds Kira in the tunnels, while Peter, Liam and Malia are able to overpower Scott; fortunately, Stiles and Kira stop them before they can kill him, revealing Scott's transformation. Scott attacks Liam, but Liam is able to bring him back to himself, and Scott tears the Berserker armor from his body, breaking Kate's spell and reversing the transformation. Back in Beacon Hills, Sheriff Stilinski enters the school basement and destroys the Berserker using the Mute's claymore mine. In La Iglesia, Braeden is attacked by Kate and the other Berserker, but Chris, Parrish and the Calaveras arrive as reinforcements, and a battle ensues. Amid the chaos, Derek apparently dies from his injuries. Just as Kate and Araya face off, a huge black wolf appears and attacks Kate, brutally overpowering her. The wolf then transforms into Derek, who reveals that his temporary "death" was actually his body evolving into a new form; he is a werewolf again, and can now shift into a full wolf, just like his mother and sister before him. Derek destroys the other Berserker by crushing the bear skull on its head, causing it to disintegrate. Chris shoots Kate with a bullet containing the rare strain of wolfsbane that Garrett and Violet used on Brett and Liam. Injured, Kate escapes into the tunnels; Chris pursues her, and during a confrontation between them, Kate reveals that she tried to kill Scott because she thought that he and his friends had killed Allison. Chris tells her the truth about Allison's death, and Kate flees. Elsewhere, Scott deduces that Peter knew too much about Kate and the Berserkers, and therefore must have been working with Kate. Peter reveals his true plan and attacks Scott; the pair clash in an all-out fight. Peter appears to be winning, until Scott finally embraces his true nature to defend Liam, unleashes his full Alpha power, and easily defeats Peter. In the aftermath of the battle, Chris leaves with the Calaveras to hunt down Kate. Braeden informs Derek that she was formerly a U.S. Marshall, but that she was fired after she became too obsessed with finding a particular target - the Desert Wolf. Lydia gives Parrish a copy of the Argents' bestiary and offers to help him identify what kind of supernatural creature he is. Noshiko informs Kira that she reshaped a chunk of obsidian that Kira used to trigger her healing in the tunnels into a throwing star, and Kira realizes that the throwing star represents her first Kitsune tail. Peter is locked up in the supernatural wing at Eichen House, in the same room as Dr. Valack. After looking into Valack's third eye, Peter becomes terrified and makes a desperate but useless attempt to flee. Peter's fate, and Valack's intentions toward him, remain unrevealed.

Scott, Stiles, Lydia, Kira and Malia prepare for their senior year. Sheriff Stilinski is threatened by a teenage delinquent named Donovan. Kira comes back to Beacon Hills after spending the summer in New York. Stiles and Malia are continuing their search for Malia's biological mother, the Desert Wolf, while Stiles is struggling with the fear that he will lose his high school friends when they all go to college. A strange, mutated werewolf named Belasko hunts down Scott, intending to steal his Alpha power. Scott and Kira are able to fight off Belasko with the help of another Beta werewolf, who introduces himself as Theo, an old friend of Scott and Stiles. Theo says that he's come back to Beacon Hills to join Scott's pack. Belasko meets with his masters, the Dread Doctors, and is executed by their leader, the Surgeon. In a flash-forward, Lydia is being held in Eichen House; she's questioned by Dr. Valack, and says that her friends are all going to die.

Deaton informs Scott that Belasko's claws were actually the talons of a harpy eagle, and warns him that someone may be trying to change the rules of their supernatural world. Stiles investigates Theo, as he's convinced that Theo is up to no good. Liam reveals his true nature as a werewolf to his best friend Mason, and tells him about the supernatural world. Lydia and Parrish try to help a girl named Tracy, who has been suffering from hallucinations and night terrors. Tracy later wanders into the lair of the Doctors, who inject her with a serum that turns her into a werewolf.

Tracy goes on a killing spree, brutally murdering her father and her psychiatrist. Liam, Mason and Brett discover that Tracy was buried alive in the woods and dug her way out of the ground. Lydia and Kira figure out that Tracy is still trapped in a night terror and thinks that she's still asleep. Scott, Stiles and Malia bring Tracy to Deaton at the vet clinic, where Tracy grows a tail and is revealed to be a Kanima. She paralyzes Scott, Stiles, Deaton and Malia and escapes, breaking through a barrier of mountain ash with ease. Tracy then goes after Lydia's mother at the police station; during the resulting fight, Kira unleashes her Kitsune powers and manages to cut off Tracy's tail, but Lydia is badly injured. Malia arrives and manages to subdue Tracy, but the Doctors immediately appear, and the Surgeon kills Tracy in front of Malia.

In a flashback, Parrish tells Lydia about a dream where he carries a body to the Nemeton before setting himself on fire. In the present, the Doctors abduct Donovan and transform him into a supernatural creature, and Theo is revealed to be working with the Doctors. Lydia undergoes surgery in the hospital, and asks Parrish to teach her how to fight. Deaton informs Scott that Belasko was a werewolf-Garuda hybrid, while Tracy was a werewolf-Kanima hybrid. They were both made artificially, explaining why Tracy was immune to mountain ash: someone is creating hybrid supernatural creatures, which Scott dubs Chimeras. Liam agrees to be Mason's wingman at a nightclub. While there, Liam argues with a girl named Hayden, while another Chimera, Lucas, tries to seduce Mason. Scott, Kira, Liam, and Brett manage to subdue Lucas, who is revealed to be a werewolf-scorpion hybrid. Kira loses control and attempts to kill Lucas, but Scott stops her. The Doctors appear and kill Lucas themselves, stating that he was a failure. Malia discovers a book in Tracy's bedroom called "The Dread Doctors,” featuring pictures of the Doctors on its cover. Parrish takes Lucas's body to the Nemeton in a trance and sets them both ablaze. Elsewhere, Stiles is attacked by Donovan, who has been fully transformed into a Chimera.

Donovan, who is revealed as a wendigo-lamprey hybrid, chases Stiles into the school library, where Stiles accidentally kills him in self-defense. Parrish steals the bodies of Tracy and Donovan, and takes them into the woods in another trance. Scott overhears Kira whispering in Japanese in her sleep. Malia shows the book that she found to the others, and Scott discovers that it is dedicated to Dr. Valack, a three-eyed inmate at Eichen House. Scott, Kira, Stiles, and Lydia go to Eichen House. Stiles and Lydia question Valack, who reveals that he wrote the book under an assumed name to chronicle what happened the last time the Doctors came to Beacon Hills. Kira's electric power goes haywire, knocking out the power to the asylum, and disrupting the electromagnetic currents that are part of its supernatural security system. The Doctors enter the asylum, attack Valack, and surgically remove his third eye. Malia has a flashback while driving with Theo, and discovers that the Desert Wolf caused the car crash that killed her adopted mother and sister. An injured Valack uses a recording of Lydia's banshee scream to shatter the glass wall of his cell.

Sheriff Stilinski discovers eight large holes on the lacrosse field, suggesting that the Dread Doctors have created eight new Chimeras. Parrish begins teaching Lydia how to fight. Liam attempts to make things up to Hayden. The group begins reading Valack's book, but Kira has difficulty reading it. Mason later explains to her that it is because Kitsunes are confused by "language tricks." Theo records Kira's whispering in her sleep, and he later informs Scott that what she has been saying translates to "I am the messenger of death." Scott has an asthma attack at the high school. One of the new Chimeras, a boy named Josh, enters the school basement, and chews through the power lines, before making his way to the hospital roof. Scott, Stiles and Lydia all experience traumatic visions because of their exposure to the book. Liam discovers that Hayden is a Chimera. In the hospital, Scott and Malia are attacked by the Pathologist, one of the Doctors, but they manage to escape. Meanwhile, Stiles goes to the roof of the hospital during a hallucination. Josh, the new Chimera, attacks Stiles, but Theo rescues him and kills Josh.

Theo convinces Stiles to help him conceal the truth about Josh's death. Hayden is attacked by the Doctors, but Liam rescues her and takes her home. However, she then transforms into a werewolf. Mason befriends Corey, Lucas's ex-boyfriend, and discovers that Corey is also a Chimera. Kira's mother, Noshiko, warns her that Kira's "inner fox" is fighting her for control. Melissa McCall and Sheriff Stilinski discover that the Chimeras had all previously received organ transplants. Theo and Stiles stake out the vet clinic to find out who is stealing the dead Chimeras. Scott, Lydia, Malia, Liam, and Parrish set up a trap in the high school, planning to protect Hayden and capture one of the Doctors. Kira disappears from her house. Meanwhile, Parrish slips into another trance after seeing a hallucination of Lydia. He goes to the vet clinic, knocks Stiles and Theo unconscious, and steals Josh's body. The Doctors enter the high school, subdue Scott, Lydia and Malia using illusions, and abduct Liam and Hayden. Melissa finds a dead Chimera girl in her house, who has been impaled by Kira's katana.

Deaton investigates the Doctors, but he is confronted by the Desert Wolf. Kira is arrested for the murder of the Chimera girl, but her father Ken confesses to the crime to protect her. The Doctors begin experimenting on Liam and Hayden. Scott accesses Corey's memories and discovers that the Doctors took him to a water plant. Liam and Hayden meet another Chimera, Zack, who has amputated wings on his back. Zach explains that the Doctors kill their failed Chimeras when they start bleeding mercury. Scott, Malia, and Mason go to the water plant to rescue Liam and Hayden, but they cannot find them. The Doctors kill Zack when he begins bleeding mercury. Theo and Lydia discover that Liam and Hayden are being held in the abandoned house where Belasko first appeared. Kira manages to read Valack's book by reading it backwards and discovers that the Doctors experimented on her the night she first came back to Beacon Hills. At the hospital, Parrish goes into another trance, attacks the police officers guarding the female Chimera's body, and steals the body. Theo rescues Liam and Hayden. Kira decides to leave Beacon Hills with her family because she does not want to hurt anyone else until she can understand what the Doctors did to her. Stiles and Lydia find out that Parrish is the person stealing the bodies. The Desert Wolf tells Deaton that she intends to kill Malia.

Scott struggles with the return of his asthma and a growing feeling of hopelessness. Theo asks the Doctors to leave Hayden alive. Hayden begins bleeding mercury, while Corey begins vomiting blood and mercury who is taken to the hospital. Theo tells Scott that Stiles murdered Donovan, leaving out that it was in self-defense. Another girl named Beth is revealed as a Chimera. Malia tries to help her, but Beth is killed by the Pathologist outside the school. Scott and Theo follow Corey to the hospital. Corey tries to escape the hospital, but he is found and killed by the Surgeon. Lydia and Parrish find the Nemeton, where Parrish has left the dead Chimeras. Parrish is horrified, and tells Lydia that in his dream, there were hundreds of bodies at the Nemeton. Theo lies to Sheriff Stilinski, claiming that he killed Donovan in self-defense. Liam and Hayden decide to go on the run, but they are confronted by the Doctors. Scott, Theo, and Liam fight the Surgeon and the Pathologist, while the third Doctor, the Geneticist, injects Hayden with an unknown chemical. Parrish locks himself in a cell at the police station to keep himself from hurting anyone else. Scott confronts Stiles at the vet clinic, and they fight over Stiles killing Donovan. Stiles leaves after Scott refuses to believe that he is innocent. Hayden's condition begins rapidly worsening. Liam asks Scott to bite Hayden, hoping that it will heal her, but Scott refuses to do so.

Scott argues that Hayden is too weak and will die if he bites her. A mysterious creature rampages through Beacon Hills. Scott, Liam, and Theo enlist Melissa to treat Hayden at the vet clinic. Scott explains that the upcoming full moon, a "supermoon", will make the werewolves much stronger and more aggressive than normal. Lydia discovers that Parrish is a hellhound and has a premonition that someone is going to die in the school library, but Theo appears and knocks her unconscious. He then locks Malia up at the hospital, and then abducts and injures Sheriff Stilinski. Scott goes to the school, where Theo traps him in the library by using mountain ash. Theo reveals that he is the first Chimera, a werewolf/werecoyote hybrid, and leaves Scott trapped in the library. Scott discovers that Theo was poisoning him by putting wolfsbane in his inhaler. Malia escapes the room she was trapped in, but is then attacked by one of the two remaining Chimeras. However, Braeden appears, rescues her, and warns her that the Desert Wolf is coming to Beacon Hills. Liam appears at the library, supercharged by the moon and enraged over Hayden's condition, and attacks Scott. Theo confronts Stiles and reveals that he came back to Beacon Hills to kill Scott so that he can create a pack of villains. He then gives Stiles the choice of either going after Scott or saving his father. Hayden dies at the hospital. Scott and Liam engage in a vicious fight: Liam has the advantage, due to Scott's wolfsbane poisoning and his unwillingness to kill Liam, but Mason appears and snaps Liam out of his enraged state by telling him that Hayden is dead. Liam leaves, but Theo then appears and kills Scott. However, Melissa is able to revive him. Stiles finds and rescues Sheriff Stilinski. Liam allows Parrish to take Hayden's body. Theo accesses Lydia's memories, leaving her catatonic, and brings her to the Nemeton, where he injects Tracy, Corey, Josh, and Hayden with a liquid that brings them all back to life as his own pack. The Doctors uncover a painting depicting an epic battle between a hellhound and another unknown creature.

Scott and Stiles must strive to figure out what's behind the mysterious infection that's killing the town sheriff in spite of their deep rift.

Hayden and Liam are attacked by a massive, shadowy creature, which Scott later identifies as the Doctors' last Chimera. Scott and Stiles reconcile and begin investigating the creature, while Theo trains his new Chimera pack. Malia and Braeden discover that the Desert Wolf is on her way to Beacon Hills with Deaton hostage. Lydia has a dream of Meredith, who promises to teach her how to control her banshee powers. Scott and Stiles deduce that the monster is an ancient supernatural creature that was recreated by the Dread Doctors, and decide that they need to reunite their pack. Chris visits Gerard, heals him using a strange plant, and interrogates him about the last Chimera. Gerard reveals that the creature is the Beast of Gevaudan. Kira and her mother are in New Mexico, where they are confronted by a trio of Skinwalkers.

Theo and Tracy are confronted by the Doctors and the Beast, after Theo reveals that the Doctors are trying to help the Beast remember its past self and unleash its full power. Meanwhile, the Skinwalkers inform Kira and Noshiko that they intend to test Kira to see if she can learn control; if not, they will turn her into a Skinwalker. Scott and Stiles go in search of Kira, and reconcile along the way; in the process, Scott deduces that Malia intends to kill her mother, the Desert Wolf. At Eichen House, Meredith continues teaching Lydia how to use her banshee powers. Kira's test begins, as the Skinwalkers summon an Oni for her to fight; however, Kira's inner fox takes control of her and destroys the Oni, thereby failing the test. The Skinwalkers attempt to force Kira to stay, but Scott and Stiles arrive in time to rescue her and Noshiko. Scott and Kira get back together as they return home. Liam and Mason tell Scott that they've learned Theo is trying to find a blind Alpha, and Scott realizes that Theo is looking for Deucalion.

Chris and Gerard discover twenty-three bodies in the sewer tunnels, victims of the Beast. Theo helps Malia to locate the Desert Wolf and Deaton. Scott and Liam find the Doctors' lair, where they meet up with Chris and Gerard and decipher the painting depicting a battle between the Beast and a Hellhound. Chris and Gerard help Parrish to realize that he is a hellhound. Malia, Braeden and Theo track down the Desert Wolf and find Deaton, but Theo betrays them, shoots Malia, and hands her over to the Desert Wolf in exchange for Belasko's claws. The Desert Wolf reveals that she wants to kill Malia because she lost part of her powers when Malia was born, and she intends to reabsorb them from Malia. Before she can kill Malia, the Beast appears and attacks them all; Malia, Braeden and Deaton escape, but the Desert Wolf gets away too. Lydia completes her training with Meredith, obtains control over her banshee powers, and tries to escape Eichen House, but is recaptured. Theo meets with his pack, who have captured Deucalion; Deucalion, who has gone blind again, deduces that Theo wants his help in stealing the Beast's power, and demands Scott's eyes in exchange. Scott and his friends reunite their pack and begin planning to break Lydia out of Eichen House.

Scott and his pack make a plan to get Lydia out of Eichen House. But Theo and his pack also want to get into Eichen House, Theo offers Scott to help, but what he really wants is the Hellhound. Stiles gets to Lydia, but she tells him to go away or he'll die. Scott tries to get trough the Mountain Ash but he fails. Liam and Scott get attacked by Security guards, but somehow Scott gets really strong and tell Liam he's going to get Lydia.

Parrish easily overpowers Tracy, Josh and Corey, but Theo disables him by impaling him; meanwhile, Valack escapes with Lydia, and Stiles and Theo pursues them. Scott and Liam find Meredith, who tells Scott that Parrish can find Lydia. Kira's electricity begins to overload, but Josh helps her by absorbing the electricity; in exchange, Malia helps to heal Corey, who was badly burned by Parrish. Valack plans to increase Lydia's power so that she can discover the identity of the Beast, and reveals that he intends to put a Dread Doctor helmet on her; however, Lydia loses control and unleashes a scream that kills Valack. Scott and Liam help Parrish transform back into his Hellhound form. Stiles and Theo rescue Lydia, while Parrish burns through the mountain ash barrier, allowing Scott and Liam to follow him. Lydia begins to unleash a deadly scream, but Parrish smothers the scream and saves the others. Mason and Hayden restore power to Eichen House, and the packs escape. Scott and Stiles rush Lydia to Deaton, who heals her.

Parrish fights the Beast at the school, but loses, as the Beast is getting smarter. Mason deduces that the Doctors are using high-frequency radio signals to trigger the Beast's shifts, and the pack realize that the Beast may be summoned again at the upcoming lacrosse game. Scott and Stiles find Bobby Finstock in rehab, and convince him to coach the game, planning on having him forfeit the game; however, Finstock refuses to do so and the game begins. Scott convinces Brett and his sister Lori to help them. With help, Parrish is able to access his Hellhound side, who informs Lydia that it possessed Parrish when he died defusing a bomb. At the game, Kira loses control and injures players, before storming off. Kira almost kills Lori, but Scott stops her. Mason and Corey search for the Beast's human form at the game, while Malia disables the broadcast antennas. Interrupted by the Desert Wolf, the news broadcast begins. The Beast immediately appears, and overpowers Liam before going on a rampage through the high school.

Parrish leaves, believing himself to be too dangerous. Chris and Gerard tell Lydia the story of Marie-Jeanne Valet, the first werewolf hunter and the woman who killed the first Beast of Gévaudan. With help from her allies, including a man named Henri Argent, she hunted down and killed the Beast, which was revealed to be her brother Sebastien. Marie-Jeanne married Henri and took his surname; they went on to start the Argent family of hunters. Gerard suggests that Lydia might be able to kill the Beast, but she insists that they need Parrish and leaves to find him. Meanwhile, Scott takes on the Beast at the school, while Stiles and Hayden manage to heal Liam. Scott fights the Beast in the school library, after transforming in front of numerous students, and is losing until Liam, Malia and Braeden come to help him. The four of them manage to drive the Beast out of the school, and Scott follows its scent to a car where they find a pair of bloody sneakers. Mason shows up and reveals that it's his car, and Scott and Liam realize that Mason is the Beast's human form. Before any of them can do anything, Corey appears and abducts Mason.

Mason is abducted by the Dread Doctors. Lydia and Sheriff Stilinski persuade Parrish to remain in Beacon Hills and to fight the Beast. Deucalion reveals that he could have escaped from Theo at any time, and advises Theo on what to do next. Theo kills Josh and absorbs his power, allowing him to wear the Dread Doctor helmet to discern the Beast's identity; however, he doesn't see Mason. Scott, Liam and Theo team up and find Mason at the Doctors' lair, but they are cornered by the Doctors. Malia and Braeden are confronted by the Desert Wolf at Scott's house; the Desert Wolf gets past the mountain ash barrier, but Braeden recreates the barrier and traps the Desert Wolf inside the house with Malia. Kira returns to the desert and requests the Skinwalkers' help. The Doctors easily overpower Scott, Liam and Theo, but Mason then naturally transforms into the Beast. The Beast kills the Doctors, before Parrish, Chris and Gerard arrive and join the fight. The Beast reverts back to human form, but transforms into Sebastien instead of Mason.

Sebastien searches for the Surgeon's cane-sword, which Gerard reveals was once the spear that Marie-Jeanne used to kill the first Beast. It's revealed that the Surgeon was actually Marcel, Sebastien's old friend; he then dies. Theo kills Tracy and takes her power. Sebastien pays a visit to the Sheriff's station, threatens the Sheriff and injures Lydia and Hayden. Deaton reveals that a part of Mason is still inside Sebastien, and that Lydia is the answer to saving him. Deucalion double-crosses Theo and reveals that he was actually working with Scott the whole time. Malia uses Belasko's talons to take away what’s left of the Desert Wolf’s power and successfully defeats her. Parrish, Chris, Scott and Liam fight Sebastien, but are losing, until Kira returns and brings Lydia to the Beast; Lydia screams Mason's name, separating Mason from the Beast. Parrish pins the Beast down and Scott impales it with the cane-sword, killing it. A furious Theo attacks the pack, but Kira opens up the ground and summons Theo's dead sister, who drags him into the hole before it disappears. Later on, Scott turns Hayden into a real werewolf, Stiles decides to become a cop like his dad, and Kira leaves with the Skinwalkers to gain control over her fox spirit. It's revealed that the Doctors' final test subject, a Nazi Alpha werewolf, has escaped from their lab.

Scott, Stiles, Lydia and Malia are preparing for their upcoming graduation. Liam and Hayden find a young boy named Alex, whose parents were abducted by a man riding a horse. Scott, Stiles, Liam and Mason later go to Alex's house, which has been abandoned, and find that all traces of Alex's parents appear to have been erased from existence. Stiles sees the same man who took Alex's parents, and they then discover that all of Alex's belongings have now vanished too. Lydia reveals that she has been hearing strange music; she and Stiles deduce that the men on horseback are Ghost Riders, part of the mythical Wild Hunt. Anyone who sees them as they pass will be abducted by them and erased from existence, forgotten by all who know them. The Ghost Riders break into the Sheriff's station and abduct Alex, who was being kept safe in one of the cells. When Scott and Stiles get to the station, they discover that everyone there has forgotten about Alex too. Meanwhile, Liam, Mason and Hayden find a dead body in the high school. Scott and Stiles go to the high school, where Stiles realizes that he is the Ghost Riders' next target, as everyone except Lydia has forgotten him. Stiles and Lydia are pursued by the Ghost Riders and surrounded. Stiles tells Lydia that she needs to find a way to remember him and that he loves her, before he is abducted by the Ghost Riders. Scott, Lydia and Malia meet up at the high school the next day, and they all seem to have forgotten Stiles completely.

Mason and Corey see the Ghost Riders abducting a student in the library, and Corey discovers that he can see the Ghost Riders when he turns invisible; however, they both forget about the abducted student as soon as it happens, and only remember that they saw the Riders. Scott, Lydia and Malia all begin having hallucinations and subconscious memories linked to Stiles. Eventually, Scott thinks back to the night he was first bitten, and realizes that there must have been another person with him that night. It's revealed that Stiles's mother, Claudia Stilinski, is somehow alive as a result of Stiles's being erased. Liam, Mason and Corey use Corey's powers in the library and find a blank library card, belonging to the student who was abducted; this helps them to remember him. Scott, Lydia, Malia and Deaton deduce that the Wild Hunt doesn't just take people, but also erases them from reality. With Deaton's help, Lydia subconsciously draws Stiles's name by writing the word "mischief" over and over in a pattern, but still doesn't remember who he is.

Mr. Douglas, a new teacher at the high school, is revealed to be the Nazi Alpha werewolf who escaped from the Dread Doctors. He kills several people by biting open their skulls and eating their pineal glands, causing Chris Argent to return to town and recruit Melissa for an investigation to find the werewolf responsible for the murders. Meanwhile, Hayden meets a student named Gwen, whose sister was abducted by the Ghost Riders. Assuming that Gwen might be the Riders' next target, Liam, Mason, Corey and Hayden throw a party at Scott's house in an attempt to keep her safe. The Riders show up; Corey uses his power to make one of them visible, allowing Liam to fight off the Rider and save Gwen. Parrish confronts the Rider, which vanishes without attacking him. Elsewhere, Scott, Lydia and Malia track down Sheriff Stilinski's father Elias, who was also nicknamed Stiles. Elias turns out to have dementia and was abusive to his son, but is revealed to remember Stiles. Scott and Liam realize that all the students who saw the Ghost Rider at the party are now targets for the Wild Hunt.

Lydia continues investigating Stiles, now looking for some sort of "relic" he might have left behind. She tries to investigate the Stilinski house, but Claudia stops her. Scott, Liam and the others attempt to protect everyone who saw the Ghost Rider at the party by taking them all to Chris's underground bunker; however, four of the kids, including Gwen, are participating in a lacrosse game at the high school. Scott, Liam and Corey participate in the game to protect them, while Chris and Malia guard the bunker and Mason deduces that Parrish may be able to stop the Riders. The Riders show up at the game and manage to abduct and erase numerous people, including Gwen. Parrish confronts one of the Riders and is shot by it, but survives. One of the students at the bunker, Nathan, allows the Riders into the tunnels by attempting to escape, and they erase him and the other students from the party. Lydia and Melissa investigate Claudia's medical records, which show that she had no children, but somehow miraculously survived her frontotemporal dementia. It's revealed that Stiles's "relic" is his Jeep, which is still in the school parking lot.

After being abducted, Stiles finds himself in an abandoned train station with many others who were also erased by the Ghost Riders. One of those people is Peter Hale, who reveals that he was abducted by the Riders after he escaped Eichen House during the power outage caused when the pack rescued Lydia. Stiles, Peter, and another prisoner attempt to figure out how to escape: the other prisoner attempts to escape through a magical barrier set up by the Riders, but the barrier incinerates him. Stiles and Peter attempt to use the train station's intercom to contact Stiles's friends, but are unsuccessful. Meanwhile, Scott, Lydia, and Malia find Stiles's Jeep in the school parking lot; Lydia deduces that it might belong to Stiles. Peter manages to make it through the barrier, but he is badly burned as a result, surviving only due to his werewolf healing ability. Scott and Malia find Peter, remember who he is, and realize that they had forgotten him too. Stiles uses the intercom again and is able to contact Scott and Lydia through the radio in his Jeep. He tells them to find "Canaan", one of the towns listed on the train station's Arrivals board.

Lydia has a vision of a town called Canaan in the 1980s, where the residents all disappeared. The gang goes to Canaan and realize that it is a ghost town, as the Riders have taken the entire population. They see a boy who leads them to the house of Lenore, a banshee who is the only remaining resident of Canaan. Lenore takes them prisoner as playmates for the boy, who is the ghost of her dead son Caleb, unconsciously summoned by her to fill the void in her life that was created by the loss of the townspeople. Caleb almost kills Scott and Malia until Lydia is able to convince Lenore to release them. Liam and Hayden devise a plan to fight the Riders. Using Kira's sword, Liam frees Theo from his purgatory.

Lydia theorizes that Claudia is a ghost like Caleb, conjured by Sheriff Stilinski to fill the void in his life created by Stiles's erasure. The pack captures a Ghost Rider and tries to interrogate it, but are unsuccessful. Mason deduces that Parrish can communicate with the Riders, but the Rider somehow triggers Parrish, who tries to free it. Scott and Liam must force him away. Malia and Melissa heal Peter's burns in return for his help finding the location of the portal to the Riders' train station. Mr. Douglas reveals his true identity and overpowers Theo, then kills the Ghost Rider and eats its pineal gland. Lydia and Sheriff Stilinski find Stiles's old bedroom behind a wall in the Stilinski house. Mr. Douglas attacks Corey with the Ghost Rider's whip and causes him to vanish like the Riders' other victims.

Mr. Douglas forces Chris and Melissa to help him find Parrish; he then erases them both and takes control of Parrish. Theo explains that Douglas was a Nazi captain, and that he wants to take control of the Ghost Riders and use them as his own supernatural army. The gang realizes that the rift's entrance is underground. The Riders erase Mason and Hayden, but Liam escapes. Mr. Douglas and a mind-controlled Parrish confront the gang at the rift; Parrish opens the rift, and Douglas and Parrish go through it. The Riders nearly kill Scott and Malia, until Peter intervenes and sacrifices himself to help them escape, being erased again. Sheriff Stilinski recovers his memories of Stiles and realizes that Claudia is dead, which causes her spirit to vanish. Scott, Lydia, Malia, Liam, Theo and Sheriff Stilinski are now the only people left in Beacon Hills; however, they realize they can open another rift by remembering Stiles.

Lydia, Malia and Scott try to remember Stiles in hopes of reopening the rift. Sheriff Stilinski is erased by the Ghost Riders. Scott and Malia each enter Parrish's freeze chamber and go into a death-like trance in the hope that it will trigger memories of Stiles, which will open a rift. They each recover their memories of Stiles, but the rift does not open. Scott then hypnotizes Lydia, which brings her to the memory of when she first kissed Stiles. This finally opens the rift. Meanwhile, Liam and Theo fight the Ghost Riders to keep them from finding Scott.

Stiles makes it through the rift with help from Sheriff Stilinski. Lydia, Scott and Malia are disappointed when Stiles does not appear through the breach, but he reappears in his Jeep instead. Liam shows Scott that there are railroad tracks in the buildings all over town. Mr. Douglas and Parrish confront them, but Stiles appears and uses liquid nitrogen to subdue Parrish and free him from Douglas's control. Liam manages to find the train station and reunites with Mason and Hayden; they discover that Douglas is using Corey to merge the Ghost Riders' realm with the real world so he can gain control over them. Claudia's spirit attacks Stiles, Lydia and the sheriff, but they manage to destroy her. Scott, Malia, Peter and Theo battle Douglas and the Riders in the woods; the pack manage to divert the Riders' ghostly train past Beacon Hills and free Corey, which reverses the merging. The Riders begin to leave, but when Douglas objects to their departure, they claim him as one of their own. Everything in Beacon Hills returns to normal. On their last day of high school, Scott and Stiles discuss their future plans and drive off together in Stiles' Jeep.

Scott and Liam discover many dead wolves in the forest. A new hellhound named Hawlyn escapes from Eichen House, seeking something that Scott's pack let out when they rescued everybody from the Wild Hunt. Lydia has a premonition and convinces Malia, who was on her way to Paris, and Scott, who was preparing to leave for college, to stay in Beacon Hills to help. Tamora Monroe, the new guidance counselor with ulterior motives, kills Hawlyn before the pack can learn about the creature he was hunting. Scott deduces that Hawlyn's killer was a hunter. Stiles begins his career as an FBI intern in Virginia and is shocked to discover the FBI are pursuing Derek Hale, who they believe is a mass murderer.

Theo is attacked by a group of unknown hunters. Feeling threatened, Scott loses control of his shift and almost attacks Sheriff Stilinski. A student named Aaron is attacked by a swarm of spiders in the locker room, and Liam and Mason find a faceless body in the same room. Scott and Malia save Argent's life when his latest buyers in his gun business attempt to kill him. Argent deduces that the hellhound's killer is a new hunter. Monroe attacks Brett after figuring out he is a werewolf. Brett flees after Gerard wounds him with an arrow. Gerard recruits Monroe due to her potential as a hunter. Parrish and Lydia go to Eichen House; Parrish is nearly killed by the head doctor, Conrad Fenris, who displays the same fear of the supernatural as Monroe, but Lydia rescues him. The pack deduces that something is making the ordinary people of Beacon Hills afraid of the supernatural.

Scott, Malia, Liam and Brett's sister Lori try to find Brett, who has been poisoned and is being hunted by Gerard and Monroe. The pack tracks them into the tunnels, where Scott is injured when a hunter's tripwire is triggered. While Malia is trying to take Scott's pain away so he can heal faster, Scott, driven to delirium by the pain, reveals that he has developed romantic feelings for Malia, which both surprises and pleases her. Liam and Lori find Brett and escape the sewers. It is revealed that Gerard had set a trap; Brett and Lori are hit and killed by a truck as soon as they escape, and Liam's rage causes him to shift in front of many eyewitnesses. At the high school, Nolan stabs Corey with a pen and sees his injury heal, outing Corey as a supernatural creature. At the hospital, Melissa attempts to perform an autopsy on the faceless corpse, but is overwhelmed by terror emanating from the corpse. She enlists Argent to help her; they remove a tissue sample from it, but they discover that the corpse has no DNA.

Aaron goes to the hospital and regurgitates the swarm of spiders onto the faceless corpse, which comes back to life. Rumors about Liam's true nature spread through school. Nolan and the lacrosse team beat him up terribly to try to make him transform through anger, but he is able to resist the change until Coach Finstock intervenes. Malia, who is revealed to reciprocate Scott's feelings for her, tries to tell him of her own feelings, but is unable to spark up the courage, frustrating her. Liam learns Monroe is the new hunter, and Scott meets with her and Gerard for a peace treaty. Monroe reveals she was almost killed by the Beast of Gévaudan, for which she blames Scott's pack. The faceless corpse (the creature that escaped the Wild Hunt) attacks Scott's pack and the hunters, but Parrish repels it. A young werewolf named Quinn is shot by a deputy and later seeks sanctuary with Scott.

Deaton, Mason and Corey identify the Wild Hunt escapee as the Anuk-Ite or Double-Face, a powerful creature from Native American mythology, which feeds on the fear it creates. Theo escapes the hunters along with Jiang and Tierney, the last survivors of Satomi's pack, but the trio are arrested for murder. Scott's pack go to the police station but Monroe's hunters surround the precinct, demanding they hand over Jiang and Tierney, who killed some of her hunters to avenge Satomi. The Anuk-Ite increases everyone's fear, and two deputies kill themselves. Scott's father arrives and makes a compromise with the hunters, taking Jiang and Tierney into FBI custody, but the deputy who drives them away is loyal to Monroe and kills them. Scott's father persuades Scott's pack to flee Beacon Hills, but they only pretend to do so, having decided to fight back.

Aaron identifies a werecoyote named Edgar in school and "tests" him by transferring a spider into his body. Edgar is left slowly dying, and Monroe has him killed by Aaron, unsettling Nolan. Theo and Liam draw the hunters to an abandoned zoo, and Theo stops Liam from killing Nolan in rage, warning him that his fear of the Anuk-Ite triggers his anger. The pack breaks into Gerard's armory, discovering it empty of weapons. They find Jiang and Tierney's remains and a world map, and inadvertently activate the armory's security system, which sucks all the oxygen out of the room. Scott and Malia nearly suffocate to death, but Lydia and Argent rescue them. At the McCall home, Scott and Malia reveal their feelings for each other and kiss passionately, starting a relationship. They discover that Gerard's map indicates the locations of all the Nemetons around the world, which he plans to use to wipe out all supernaturals, and that Gerard has given all his weapons to the people of Beacon Hills. The house is suddenly attacked by gunfire, and one of them is shot.

Gerard sends hunters to London, where Jackson and Ethan, now a couple, live. Suspecting Gerard, they return to Beacon Hills to find Scott, but are captured by Monroe. Melissa, Mason, Rafael and Lydia were all shot in the gunfire attack, moving Scott to decide to form an army to combat Gerard's army. He and Malia unsuccessfully try to recruit Deucalion to join the fight. Malia recruits her father Peter Hale, who joins after he sees that Malia is in love with Scott. Scott and Malia also try to recruit another pack of werewolves known as the "Primal", but find them all dead, killed by the Anuk-Ite, with a second skinless corpse amongst them, meaning the Anuk-Ite's second half has taken the form of a werewolf. The pack discovers that Aaron is the first half of the Anuk-Ite. Lydia sees a vision of the dead Hellhound Hawlyn, who reveals that she needs to find the other half of the Anuk-Ite before it finds itself.

Lydia and Malia briefly revive Halwyn, who warns them of the Anuk-Ite's petrifying vision before the silver from Monroe's bullet poisons and finally kills him. While Mason and Theo track Aaron in the tunnels beneath the town, Scott and Liam trace a call on a dead Primal werewolf's phone to science teacher Mrs. Finch, who is revealed to be the Alpha of the Primal pack and Quinn's mother. Quinn, the other half of the Anuk-Ite, attacks Scott, Liam and Finch, while Theo wounds Aaron in a fight, inflicting pain on Quinn in the process. This enables Aaron and Quinn to find each other and merge into the complete Anuk-Ite. Later, Scott has sex with Malia, consummating their relationship. Meanwhile, the Anuk-Ite allies with Gerard to destroy Scott.

In Brazil, Argent tracks down Derek, who is searching for yellow wolfsbane. Kate, who is allied with Gerard and had framed Derek for mass murder, arrives and shoots them both, taking the wolfsbane to use against Scott. Meanwhile Gerard and Monroe distribute weapons to most of Beacon Hills' population, but Scott believes that the townspeople's fear and hatred is not real and that the war can be averted by destroying the Anuk-Ite. He and Malia enlist Deucalion to teach them how to fight without sight, so they can defeat the Anuk-Ite. Lydia has a vision of her friends petrified and turned to stone. Lydia and Peter track down Scott to warn him, but Monroe and her hunters arrive and open fire, mortally wounding Deucalion. At the same time, Nolan betrays the hunters and leads Liam to the hospital to find captured werewolves, but this is a trap Monroe set up, knowing Nolan planned to betray her. Liam, Mason and Corey are trapped in the hospital as hunters close in.

Stiles and Derek return to help Scott and the others. Decaulion dies from his injuries. Gerard broadcasts them a message which reveals the location of Jackson, Parrish, Liam, Agent McCall, Mason and Corey. Stiles and Derek are updated on the news of the hunters and the Anuk-Ite. Melissa rejuvenates Nolan and Peter looks at the Anuk-Ite, causing him to turn to stone. Jackson escapes and reunites with Lydia and Stiles. Monroe arrives at the school and shoots Scott with yellow wolfsbane while Liam and the rest, including Theo, face off against the hunters at the hospital. Sheriff Stilinski rescues Parrish while Scott faces the Anuk-Ite. While fighting it, Scott claws his eyes out to prevent himself from seeing the Anuk-Ite, and manages to defeat it with mountain ash provided by Stiles. The group members trapped at the hospital are saved by the werewolves, Parrish, Stilinski, and Agent McCall. Scott is unable to heal his eyes until Malia distracts him with a kiss. Gerard is attacked by Kate while the hunters retreat and Beacon Hills is saved. In a flashforward with a new beta named Alec, Scott and every member of his pack gather to stop Monroe.