The scene opens at night in an empty high school, where Matt lifts weights. He goes to inspect a noise. He walks into a dark classroom -- and immediately sets off dozens of mouse traps laid out on the floor. Bonnie, Elena and Tyler are setting them for Senior Prank Night. Caroline is making them. "We're about to be seniors, these are the memories that will stay with us forever, and if we don't make them now, what's the point of it all?" she says, with Elena finishing for her. Elena goes to glue Alaric's desk shut. She runs into Klaus in the hallway, but running gets her nowhere. "You are supposed to be dead, what do we do about that?" he asks. Cut to Katherine and Damon speeding down the highway. He tells her he and Elena are having a difference of opinion on how he should behave. She kisses him and he goes for it -- while driving -- for a minute, and then throws her off. Stefan wakes up in the back of the truck. Rebecca explains Klaus has been breaking his neck all afternoon. They know the doppelganger is still alive.
Stefan pounces on her. She quickly throws him off and stakes him. Klaus drags Elena down the hall, explaining he plans to make her suffer. He drags her into the gym, pretending to be a teacher and shoos all the prank-setting students out, except for a girl and boy. He compels the girl to lift her foot and the boy to beat her to death if she drops it. Damon and Katherine pull over. He throws the keys away to make her talk. She reveals the necklace and even though she doesn't know why Klaus wants it, she thinks its leverage. She asks Damon if he's willing to do whatever it takes to stop Klaus. She opens the trunk to show him unconscious Jeremy inside. Back at school, Caroline pours honey on doorknobs. Tyler nuzzles her neck. She asks if he thinks Matt will be OK. He says he thinks he's struggling and feels alone.
They resume making out, but are interrupted by Rebecca, who calls Tyler out as a werewolf. She fangs out at Caroline. Matt and Bonnie TP the pool. She tells him she knows Jeremy's been seeing Vicki. "Do you realize that just last summer, you and I were life guards at the pool and the only two problems that I had in my life were that Elena was breaking up with me and I sucked at CPR? Now Elena's dating a vampire, you're a witch, my sister's a ghost and I'm just a guy who's wondering how life got so screwed up," he says. Matt goes for more TP. As he's leaving, one of the stall doors opens. He sees "RIP Vicki Donovan" on it. Ghost Vicki's there and tries to talk to him. In the gym, the girl on one leg is struggling. Bonnie and Matt join Klaus in the gym. He wants Bonnie to undo what she did. Rebecca drags Tyler in. He explains his hybrid issues, and then force-feeds Tyler his blood. He tells Bonnie to solve his hybrid problem then, for incentive, he snaps Tyler's neck.
Stefan comes to in a parking lot with a tire iron sticking out of him. Bonnie and Matt run off to figure out the hybrid question. Rebecca sizes up Elena, her competition for Stefan. Bonnie realizes she needs Jeremy to contact the dead. Meanwhile, on a road somewhere, Katherine says there's a way to kill Klaus. Her friend Pearl knew how, but only told her daughter Anna. They're both dead. Jeremy wakes up. Stefan joins the scene in the gym. He says Elena means nothing to him and he wants to pledge his loyalty. He promises to do whatever Klaus asks. Klaus orders Stefan to kill the two kids. Klaus then smacks Elena to the ground. Stefan charges him. Finally, Klaus compels Stefan to do exactly as he says. Klaus orders him again to kill the kids. Stefan complies. Katherine intercepts Damon's text from Bonnie. Anna the ghost warns Jeremy not to help them. Damon smacks his head against the table as incentive. Anna tells Jeremy to tell them they're looking for Michael, a vampire who hunts vampires.
She says they'd be crazy to wake him. Back at the school, Caroline wakes up in the hall with Rebecca playing with her cell phone. She tells Caroline that Tyler is "dead-ish" and will be a hybrid when he wakes up. Scrolling through Caroline's phone pictures, Rebecca sees one of Elena wearing her necklace. She shows it to Elena, who says she doesn't have it. Rebecca attacks Elena, biting her neck. Klaus pulls her off. Elena says Katherine stole it. Klaus sets the gym clock for 20 minutes. He says if Bonnie hasn't found the answer by then, Stefan has to feed on Elena. Matt goes to get his stuff in the weight room but sees clothes strewn everywhere. He follows them back to the pool and sees his keys at the bottom. Vicki tries to get his attention. She kicks one of his shoes in. He looks at his phone and sees what she just said about being able to help them on his phone. He calls Bonnie and tells her about his idea. He straps weights to his waist and calls her, saying he needs to be able to talk to Vicki. She says she doesn't have the magic to bring him back.
He says she doesn't need it. "You just have to be better than I was at CPR," he says, and then he jumps in the pool and doesn't come up. Bonnie races from outside to the pool and arrives to find dead Matt, weighted and on the bottom of the pool. She dives in and undoes the weights. Back at the roadside, Damon sees a million texts on his phone from Bonnie. He leaves Jeremy and Katherine to go deal with Klaus. Katherine says the Damon she knows wouldn't have been that stupid to go back. "I wouldn't have done it for you," he tells her. On the pool side, Bonnie frantically performs CPR on Matt. As he lies there dead, he sees Vicki. She tells him to give Bonnie a message. He coughs up water and sputters back to life. In the gym, Elena tries to convince Stefan he doesn't have to feed on her. He says he can't fight it. The clock ticks down past 5 minutes. In the hallway, Tyler sputters back to life. Caroline gives him the bad news. Dripping wet, Matt tells Bonnie Vicki's message from the witch who created the spell: the hybrids are dying because the doppelganger is alive. Klaus hears this.
He'll take a hybrid over the doppelganger any day. With seconds remaining on the clock in the gym, Stefan tells Elena to run or she won't stand a chance against him. She stands there and tells him to fight. The buzzer sounds. She tells him she loves him and not to give in. He fights as long as he can; then runs. He essentially throws himself around the hallway, trying to resist tackling her. She runs into Klaus. Stefan finds a janitor's broom and breaks it in half, stabbing himself through the stomach. Klaus finds him and marvels Stefan's love for Elena is stronger than his lust for blood. He compels Stefan to turn off his love for her. Stefan fights it as long as he can, then his eyes goes cold. Klaus proclaims he's fixed Stefan, and then tells him to have a drink of Elena. Stefan charges. Elena screams. Klaus joins Tyler, Caroline and Rebecca with the message from the original witch. He doesn't think Elena needs to die. He has a hunch it's the opposite.
He feeds Tyler a vial of Elena's blood. After a fair amount of writhing and flopping on the floor, Tyler rears up, looking like a vampire... now a hybrid. Elena wakes up in the hospital, where she realizes the nurse is taking bags of her blood. The nurse explains it's for Klaus. She gives Elena something to knock her out. Outside, Klaus says the fact the original witch hated him means he should do the opposite of what she said. Klaus sends Rebecca away to get his truck. Damon shows up. Klaus is about to kill him. Damon mentions he and Katherine found Michael. Cleary distraught, Klaus tosses Damon like a ragdoll, and then disappears. Damon goes inside and finds Elena. He scoops her out of the bed and carries her out. Caroline and Tyler walk hand in hand in the hallway. He feels great and describes it like a rush. He kisses her. "This is going to be an amazing year," he says. She doesn't look so sure. Bonnie finds Matt and tells him what he did in trying to kill himself so he can make contact with Vicki was reckless.
He asks for a minute to say good bye to Vicki. Bonnie leaves. He can see Vicki. Back at his house, Damon feeds Elena bourbon. He offers to help her forget the things she doesn't want. She wants to keep all of it. He presents her with her necklace, which he stole from Katherine. Elena says Stefan's really gone this time. She watched it happen. She asks Damon where he was. He says he shouldn't have left. He promises her he'll never leave her again. They're interrupted by aloof Stefan, who saunters in and pours himself a drink. Klaus told him to protect Elena. He takes his drink and tells them to carry on. In the final shot, Jeremy and Katherine visit the Pickett tomb Anna directed him to. They find Michael dead and chained inside. He opens his eyes. The episode ends.