Tracy is visiting with Mrs. Martin, the school counselor. Tracy is having night terrors and isn't sleeping. One night terror stands out in particular.
A black crow taps on the window of her skylight. When Tracy turns to the window, she sees a robot monster staring at her. When she turns on the light it's gone. The skylight is left inexplicably open. Tracy stands on a chair to close it. A robot hand reaches out and pulls the chair out from under her.
Tracy's father finds her on the floor the next morning. She explains the skylight was sealed shut and can't be open. Mrs. Martin thinks the dream is just a reaction to anxiety. Tracy begins to cough and throws up a black liquid on Mrs. Martin's desk, including a black crow's feather.
Scott helps Deaton treat a dog. Deaton examines the talon. He's doesn't understand how a werewolf has talons nor how they could absorb Scott's power. Only a beta of Scott's own making can absorb his power - like Liam. Scott wonders if he allows a lone wolf into his pack can they absorb his power. Normally, Deaton would say no but now he's not sure. It seems like the supernatural rules are no longer rigid or that someone is trying to change them.
Stiles is at the police department with his dad. He wants Sheriff Stilinski to investigate Theo. Theo's family left town when he was around 10. His sister died in an accident when Theo was eight. His dad refuses but orders Parrish to look into the case.
Stiles gets the background check on Theo, but all he finds is a speeding ticket signed by his father. Malia remarks Stiles should feel threatened because Theo has great hair and a perfect body. She offers to torture Theo. Malia's remarks only make Stiles feel more insecure. Malia wonders why Stiles is so suspicious of Theo. Stiles explains he remembers Theo from the fourth grade and the lone wolf isn't him.
Mason is researching the supernatural because he was attacked by a beserker. He shows Liam a book of supernatural creatures and asks if any look familiar. Liam says no, but it's apparent he's lying.
Liam and Mason go to class. The only seat left open is one next to a new student. Liam seems acquainted with her and is upset he has to sit next to her. He sits down in gum stuck on his chair. The girl, chewing bubble gum, smiles deviously at Liam.
Kira and Lydia are confused Scott is in AP Biology. Scott pulls out a highlighted biology book filled with notes. He's more than prepared for class. Scott's first choice for college is UC Davis, a top school for biological and physical sciences. The teacher explains there's a weed out test the next day. Theo, the lone wolf, is also in the class.
Mason continues to talk about the supernatural. Liam encourages Mason to watch the soccer players practice to distract him.
Liam's locker is next to Bubble Gum girl. Liam wonders if she's still angry about what happened in the sixth grade. She says she's not angry. She's vengeful.
Tracy tries to open her locker and hears a strange buzzing. The shadow of the robot monster is behind her. The lights in the hall go out and she's alone. Black liquid starts oozing from the locker. A robotic body climbs out and starts crawling towards Tracy. She whispers to herself there's nothing there. Lydia breaks through the dream by asking Tracy if she's alright. As Lydia leads Tracy away there is a claw mark on her locker.
Theo tells Stiles and Scott about the night he was bitten. He was skating in a neighbor's empty pool. He lost track of time until it was late at night. Theo fell and hurt himself. As he sat at the bottom of the empty pool, a werewolf bit him. Scott explains it wasn't an accident and the Alpha wanted to turn Theo.
Theo explains how he became a lone wolf. The Alpha was dead by his first full moon; killed by two of his own betas - twins (Aiden and Ethan). Stiles doesn't believe Theo.
Theo recounts a time in fourth grade when he had an asthma attack. Scott was waiting for the principal and reassured Theo. Theo knows lone wolfs don't make it on their own and wants to be in Scott's pack. He's hoping Scott is still the same kid who makes everything okay.
Scott tells Stiles he has to give people the benefit of the doubt sometimes. Stiles insists there's something off about Theo.
Lydia meets with her mother and to discuss parasomnia. Lydia offers to help Tracy, but her mother thinks if Tracy needs more help it should come from a professional. Lydia smiles and agrees.
Lydia brings Parrish to Tracy's bedroom to investigate. He discovers the skylight isn't sealed. Parrish sees multiple dead birds on the roof, but lies and tells Tracy he didn't see anything.
Malia is in driver's training and has some kind of werecotoye flashback. She runs over all the cones and the dummy.
Stiles compares Theo's father's signatures between the speeding ticket and his admission paperwork. The signatures doesn't match. The pack doesn't understand what Stiles is insinuating. Stiles believes either Theo or his parents are lying about something. If Theo's parents are psychotic killers then Theo isn't to be trusted. Malia counters her parents are Peter Hale and The Desert Wolf, yet the pack trusts her. Frustrated Stiles leaves with Liam.
Parrish offers to watch Tracy's house off duty and Lydia offers to keep him company
Stiles and Liam follow Theo and track him through the woods. Stiles encourages Liam to be honest with Mason. As they are walking Liam falls into a hole. He finds Mason's phone and a silver necklace.
They find Theo at the bridge. He throws a white lily into the river and Liam senses Theo is grieving. Stiles realizes he's leaving a flower for his sister who died of exposure.
As Liam and Stiles leave the woods, Theo appears and confronts them. Liam stands protectively in front of Stiles. Theo doesn't understand why Stiles is so suspicious of him. Stiles confronts Theo about the different signatures. Theo explains that he came back for Scott, but also to find someone like Stiles. Someone who will protect their friends. Theo believes he's meant to be apart of their pack.
Tracy's father boards up the skylight.
Scott finds Liam and Stiles in the woods. Stiles' jeep breaks down. As he fixes it, Scott asks Stiles to give Theo the benefit of the doubt again - like he did with Derek and Kira. Stiles says he was right about Peter. Scott asks Stiles why he can't trust anyone and Stiles angrily shouts, "Because you trust everyone." He slams his hand against the engine and nearly breaks it. Scott takes away the pain and heals Stiles. The jeep starts.
Parrish sits outside Tracy's house. Unknown to Parrish, Tracy stands in the street in a trance like state.
Liam meets Mason at school and is about to tell him the truth when a black wolf starts chasing them. Liam stops running and decides to face the wolf. He growls at the wolf. The black wolf backs off and runs away. Mason discovers Liam is a werewolf.
The werewolf that chased Liam and Mason runs into the woods. He phases back to human form. It's Theo.
Kira and Scott make out and discuss Scott's aspirations to be a veterinarian. Scott tells Kira he's worried he's not smart enough to be a vet. Kira reassures Scott he is smart enough. As she reaches to turn off the light, the bulb explodes. Scott and Kira ignore the mishap and have sex.
Lydia and Parrish wait outside Tracy's house. No one has come in or out. Lydia apologizes for wasting Parrish's time, but he smiles at her and says it wasn't a total waste.
Tracy is in the robotic monsters' lair. She tries to convince herself she's asleep. The robot monsters tell Tracy she's awakening. They inject her with some kind of liquid.
Tracy is the one who left the claw marks on her locker. She is the one who broke the skylight entrance and killed the birds. After the injection, Tracy reveals her fangs and glowing eyes. She roars. She's a werewolf.
Sheriff Stilinski tells Stiles evidence has to trump instinct. Stiles realizes his dad isn't wearing his wedding ring anymore. Sheriff Stilinski tells Stiles if he's certain Theo is guilty to wait. The guilty always make a mistake.
Theo confronts his parents or the people posing as his parents. He tells his "father" he was suppose to practice the signature. It was suppose to be perfect. Theo's "father" is visibly scared and apologizes profusely. Theo says the only way to explain the difference in signatures is a broken hand. He smashes his "father's" hand with a hammer.
The final image is of the river where Theo left the lily for his sister. The song, "Daisy Bell" eerily plays overhead.