Scott and Stiles are helping Sherrif Stalinski get ready for a date. He won't tell them who he's going out with.
Parrish assist with a prison transfer. Mr. Stewart, the lawyer, tells the prisoner the DA's offer during the transfer - three to five years. The prisoner, Donovan, starts to scream the Sheriffs' name. He threatens to kill the Sheriff.
Stiles sarcastically tells Donovan how awesome his performance was and how he'll have plenty of time to work on it while he's stuck in his tiny cell. Donovan lunges at Stiles. As he's led away, Stiles informs Scott Donovan wanted to be a cop.
During the transfer, the driver has what seems like a heart attack and loses control of the car. Mr. Stewart gets control of the van. There's something on the roof. It's Tracy. She attacks the officers. Tracy promises her father nothing will ever happen him and kills him.
Donovan escapes. As he runs away the Robot Doctors take him prisoner. They drill into his skull and his eyes turn a metallic color.
Stiles' jeep won't start. He tells Scott he's anxious. He shows Scott some information he found on the Desert Wolf. Whatever she's done, it's incredibly violent.
Lydia and Kira are giving Malia driving lessons, but she's having flashbacks to the car accident. Malia shakes off the memory, but she's a horrible driver. She makes a U turn, but instead of the road leading back to the school, it routes the girls downtown.
Kira suggests they turn around, but Lydia senses something and tells Malia to keep going. The girls discover the bodies of the dead officers.
The Sheriff asks Scott is Donovan is like him, but he says no. The Sheriff asks Scott to track Donovan.
Scott finds Donovan. Over the radio, Scott tells Stalinski Donovan is completely freaked out and repeating the same name. Stiles thinks the name is Theo, but it's Tracy.
The pack meets in the school parking lot and Lydia explains Tracy was having night terrors. Scott tells the pack Tracy is one lone wolf and they can find her. Malia wants to put her down. Scott wants to concentrate on catching her first.
Donovan asks for his lawyer, but he's dead. Stalinski asks Donovan to tell him what he saw. Donovan refuses and demands a new lawyer. He's experiencing some kind of mental pain from the injection.
Parrish informs Stalinski that Tracy killed her psychiatrist. Sheriff Stalinkski tells Parrish to inform Scott, but to ask him not to get involved yet.
Stiles shows Malia the information Braeden shared on the Desert Wolf. The Desert Wolf killed some men and Stiles reassures Malia they were bad guys. Malia believes they deserved it then, but Stiles doesn't believe anyone deserves what the Desert Wolf did. The image on Stiles' phone is of several mutilated bodies.
Scott earned a B on his test so the science teacher asks him to lead the class in a review of last night's reading. Liam motions from outside the class. Scott uses his super hearing as Liam tells him Tracy is in Mr. Yukimura's class.
Tracy is nearly wolfing out. She breaks the desk. Hailey asks Tracy if she's alright. Liam sets off the fire alarm. Tracy refuses to leave the class.
Scott enters the class. Tracy reaches out and grabs Hailey's arm. Tracy is having flashes of the Robot Doctors. Scott tells Tracy to let go of Hailey and she does. Hailey's arm is bleeding. Tracy says, "They are coming for all of us." She collapses and a metallic fluid comes out of her mouth.
Liam tells Hailey they are taking Tracy to the hospital. He offers to bring Hailey to the nurse, but she refuses. She goes to the bathroom and washes the blood away. The wound is already healed.
Lydia asks if they know who Tracy's alpha is. Kira suggests asking the old alpha and her pack. Liam finds Brett playing on the Lacrosse field.
Deaton cares for Tracy. Malia wants to kill her, but Deaton and Scott refuse. Deaton uses mountain ash for extra security.
Kira and Lydia go to Tracy's room because Lydia is following a feeling.
Scott and Stiles hold Tracy down as Deaton attempts to slice her arm with a scalpel. The scalpel breaks without slicing Tracy's skin.
Liam shows Brett a picture of Tracy, but he doesn't know her. She's not part of his pack. Liam notices Tracy is wearing the silver necklace he saw in the hole in the photo.
Lydia and Kira discuss why Tracy killed her father. Lydia believes Tracy wasn't in control, but Kira argues it wasn't a full moon. Lydia explains there are cases of people murdering their whole families during night terrors. If Tracy is killing people she doesn't want to kill, then she might not be awake. Lydia realizes Tracy believes she's in a night terror.
Mrs. McCall texts Scott and tells him the driver didn't have a heart attack. His body just locked up like he was paralyzed. Stiles thinks he's figured out what Tracy is. Deaton asks him to inform the rest of them, because whatever Tracy is it's not good.
Deaton has Tracy's flipped on her stomach. Something is crawling inside her spine. Her spine wavers back and forth and then suddenly her back splits open. A tail springs from her split back and smacks Stiles and Deaton to the ground.
Tracy springs to her feet and slices Malia's wrist with her tail and knocks Scott down with her claws. Tracy escapes and crosses over the mountain ash. Everyone is paralyzed. Stiles says, "She's not a werewolf!" and Scott responds, "Kanima."
Deaton doesn't know how Tracy escaped if she's a kanima. No supernatural creature can cross mountain ash. Deaton coaches Malia and Scott on how to focus on healing.
Liam, Brett and Mason search for the hole. Mason falls in it. There's no necklace. Mason realizes it's not a sink hole as Liam originally thought, but a grave. They realize Tracy was buried.
Malia heals the fastest and goes after Tracy. Scott orders Malia to save Tracy.
Kira and Lydia believe Tracy is searching for the people who tried to help her. Lydia realizes Tracy is going after her mother. Mrs. Martin is on a date with Sheriff Stalinski.
Mrs. Martin and the Sheriff meet at the police department. One of the police officers is paralyzed. Lydia and Kira arrive and warn her mother. Tracy is on the ceiling.
Liam search the grave for the necklace. He can't find it, but he believes it's a different grave. Mason questions if Tracy didn't crawl out of that grave...then who did?
Tracy attacks Stalinski and paralyzes him. Kira fights Tracy. Lydia tells her mother to run. Tracy stabs Lydia with her tail. Kira ignites in a flame and chops Tracy's tail off. Tracy runs away.
Theo finds Scott, Stiles and Deaton and offers to help. Scott lets him.
Malia finds the Sheriff paralyzed and Lydia bleeding out as Kira holds pressure on the wound. Lydia tells Malia she has to explain to Tracy she's not dreaming. Stalinski directs Malia to the basesment where Tracy and Mrs. Martin are.
Malia finds Tracy dragging Mrs. Martin's body. Malia and Tracy fight. Malia gets the upper hand and almost crushes Tracy's windpipe with her knee. Just as she's about to kill her, Malia releases Tracy. Malia tells Tracy she's not dreaming. Tracy asks, "What's happening to me?"
Suddenly the robot doctors show up. One slams Malia against a wall while another injects a metallic liquid into Tracy and kills her. Malia slips to the floor, devastated and horrified.