As they try to figure out what that means, the battery from the Jeep comes flying through the window.
Stiles thinks they need to run, but Scott insists on taking a look first. The coast is clear, so they creep back out into the hallway. Stiles suggests they find a room with fewer windows, and Scott suggests the boys locker room. He tells Stiles to call his dad, thinking that a parking lot full of cop cars will scare the alpha off. Stiles is concerned that if he does that the alpha will kill all the cops, including his dad. It took a wolfsbane bullet to slow Derek down, so he figures regular bullets won't do much to the alpha but piss it off. Running is still the only idea Scott has. Stiles points out that the school is about a mile from anything useful, so Scott suggests taking Derek's car. Stiles thinks that could work. They can take the keys off his body and go. Scott adds that they'll take Derek's body with them, although Stiles is nonplussed about the idea.
They're about to head back out when Scott pulls Stiles to a stop because he heard something. They decide to hide in lockers, even though Scott thinks that's stupid. A janitor nearly has a heart attack when he finds them in there, and he forces them both out. Just as he's throwing them out of the locker room, he's grabbed by the alpha. Scott tries to go back in to help him, but Stiles grabs him and forces him to run instead.
Meanwhile, Allison is waiting in the driveway for Scott. Jackson calls and tells her they're coming to get her, because Scott is 26 minutes late. They pull up and insist she get in the car. Allison then gets a message, which isn't an apology from Scott.
Stiles and Scott run for a set of doors at the end of the hallway. They try to bust through, but there's a Dumpster on the other side holding the doors closed. Stiles shoves at the door in desperation and announces that he's not dying at school, of all places. Scott makes him stop, although why he doesn't use his super strength to push open the door is anyone's guess. Stiles asks what the alpha wants, and Scott tells him that it wants a pack. "Oh, great, a psychotic werewolf who's into teamwork. That's beautiful," Stiles replies.
Scott and Stiles run into a basement full of old lockers, with the alpha close on their tails. It doesn't quite seem to know where they are, and Scott motions for Stiles to run. Stiles decides that they need to do more than just run. They spot a lockable room, and he decides that they're going to try to trap it. He pulls out his keys and tosses them into the room. When the alpha goes for it, he slams the door shut, and they try to block it with a desk. It seems to have worked, and the boys smile at their cleverness.
Outside, Lydia and Jackson wait in the car without talking. They're facing Stiles's Jeep, and Jackson notices that the hood looks crappier than usual. He goes to take a look, and Lydia insists on going with him. There are claw marks on the hood. Jackson is more disturbed by this than Lydia and starts backing away toward the school.
Allison walks through the dark hallways calling Scott's name.
Jackson and Lydia enter the school, and Lydia announces that she has to use the bathroom. Jackson tells her that he's starting to get tired of her and her annoying habits. As soon as she's gone, Jackson turns to see a form looming in the hallway. He thinks it's Scott at first, then he's afraid that it's Derek. But it's actually the alpha. He starts huffing in panic and touches the wounds on his neck. Lydia returns, and Jackson tells her he hasn't found the others.
Allison asks Scott what's going on and what that thing was. Scott just moves away from her and doesn't say anything. Stiles takes over and tells them that someone killed the janitor. Everyone starts to freak out then. Lydia says that it was supposed to be over because the mountain lion is dead. Jackson says that it was never a mountain lion to begin with, and Allison demands to know what the killer wants. She asks who it is, and in desperation, Scott tells them it's Derek.
Scott keeps going with this story, telling everyone that Derek has been killing people around town. If they don't escape, he's going to kill them, too. Jackson suggests calling the cops, but Stiles tells him no, arguing that they don't know what he's armed with. "Your dad is armed with an entire Sheriff's department. Call him!" Jackson argues reasonably. Lydia calls 911, but the operator hangs up on her. They got a tip that there would be prank calls about a break-in at the high school. If she calls again, they'll trace the call and arrest her. Allison tells her to call again, but Stiles explains that they won't trace a cell and will instead go to Lydia's house before coming to the school.
Allison wants to know why Derek would be killing anyone, and everyone looks at Scott for an answer. Scott gets extra defensive, and Stiles pulls him aside to calm things down. He congratulates him on throwing Derek under the bus in a not entirely approving way, and Scott figured that if Derek was dead he wouldn't mind. What Scott can't figure out is why the alpha is cornering them rather than killing them. Derek told him that the alpha wants revenge, so maybe it was about getting Allison to the school to kill her.
Jackson breaks up their pow-wow and suggests that Stiles call his dad and tell him to send someone with a gun and decent aim. Stiles won't drag his dad into this, and Jackson goes after Stiles to steal his phone. Stiles punches him in the face. Allison goes to see if Jackson is okay, and Stiles gives in. He calls his dad and gets voicemail. He leaves a message just as the alpha starts trying to bust in the door. As they all watch the door rattling to pieces, Stiles says that the door from the kitchen leads to the stairwell. "Which only goes up!" Scott says. "Up is better than here," Stiles replies.
Scott says that he's going to go get the key. Allison tells him that he can't go out there unarmed, and Lydia points out that she can make a self-igniting molotov cocktail from the chemicals in the lab. Everyone gives her a stunned look, and she tries to play innocent. Jackson smashes open the cabinet, and Lydia gets to mixing. She asks Jackson for the sulphuric acid, but he's not sure which bottle it is and just hands her one. Scott takes the flask, but Allison tries to tell him that he can't go. She explains that he has a tell and she knows he's been lying all night. Jackson smirks.
Allison begs Scott not to go, but he tells Stiles to lock the door behind him. Allison kisses him goodbye.
Allison doesn't understand why Scott went out there. She can't stop her hands from shaking, and Jackson tries to comfort her. He smirks a little when she accepts his kindness, because it means she's coming under his influence.
The others pull Jackson up from the floor, but he insists that he's okay. He bats Stiles's hand away when he tries to get a look at the wounds.
Scott walks back toward the Chemistry lab under the alpha's thrall. He puts the key in the door, which no one hears, but he stops when he hears Allison ask where he is. Memories of her flood through him, and he breaks the key off in the door to keep himself from getting in. Allison starts freaking out, but Lydia tell her to stop and listen. She can hear sirens.
When they look out the window, Derek's car is gone. The Sheriff and one other cruiser pull up. Scott is out in the hallway trying to shift back.
Scott and Stiles confirm to the Sheriff that it was Derek they saw. Scott asks about the janitor, but the Sheriff insists that they checked under the bleachers and didn't find him. Scott knows the Sheriff doesn't believe him, but the Sheriff tells him that they will keep looking.
Scott catches up with Allison and asks if she's okay. She's trying to not cry as she tells him that she doesn't understand why he did such a crazy thing. She doesn't feel like she can trust him. He tries to make excuses, but she tells him not to call and walks away.