Original vampire Klaus forces captured Katherine to torture herself. Meanwhile Klaus takes henchman witch Maddox's advice to possess Alaric's body and use his history teacher job as cover to work on the school-kids and attend the high-school 1960s theme dance, where he hopes to tempt Bonnie to overexert her hundredfold witch powers against an unbreakable charm until she dies. Jeremy mistrusts Bonnie's assurance she can cope and consults Damon, who doesn't even confide in Stefan, to brilliantly mount an elaborate trap. Matt teams up with the sheriff for Caroline's sake.
Klaus uses his power to compel Katherine to torture herself and he discovers that Bonnie is a powerful witch now. Maddox uses a spell to protect Klaus and he goes to the high-school party based on the 60s using Alaric's Body. Meanwhile Stefan and Damon transfer their house to Elena to have a safe house for her. Jeremy, Bonnie, Elena, Stefan and Damon go to the dancing party and Klaus creates a distraction to abduct Elena and Bonnie with the intention of killing her by overusing her powers to vanquish him. Matt lures Caroline and plots a scheme with Sheriff Forbes.
As the high school prepares to throw a "1960s Decade Dance," Elena starts receiving disturbing messages from Klaus via an unusual source. Bonnie tries to reassure Jeremy that she is strong enough to help Elena, but a worried Jeremy asks Stefan for advice. Caroline talks Matt into taking her to the dance. Expecting Klaus to show up at the dance, Damon and Alaric attend as chaperones, but Klaus is playing a complicated game that keeps them on edge. Finally, Damon comes up with a new plan of action that shocks and upsets everyone.
- Klaus-as-Alaric goes rooting through his vessel's closet. Katherine (Nina Dobrev) his captive briefs him on everything he needs to know to pass as Alaric (Matthew Davis), including that Jenna is mad at him. He wants Elijah to stay dead for now.
Alaric compels Katherine and she tells him about the attempt to get Bonnie (Kat Graham) more powers. Katherine begs Klaus to kill her.
"I searched for you for 500 years, your death is going to last at least half that long," he tells her.
He gives her a knife and tells her to stab herself. She drives it in her leg. He compels her to continue to stab herself repeatedly while he's gone.
Elena (Nina Dobrev) signs all the paperwork to put the Salvatore house in her name.
Outside, Damon (Ian Somerhalder) and Stefan (Paul Wesley) wonder how Bonnie is supposed to find Klaus now that she has more power. They think Klaus has already killed Katherine.
Elena invites Stefan in but makes Damon promise to play by her rules.
They don't want Elena to go to school but Bonnie assures them she can handle Klaus.
Matt (Zach Roerig) visits the sheriff (Marguerite MacIntyre), who wants him to keep faking it with Caroline (Candice King), including taking her to the dance that night. He doesn't think he can. But she needs some time to digest the fact her daughter and the Salvatores are vampires and Tyler is a werewolf.
Ric comes to teach class, with Elena and Stefan in class. He sees her almost immediately.
The school is getting ready for a 60s themed dance that night. Caroline sees Matt and kisses him hello.
Jeremy (Steven R. McQueen) wants Bonnie to tell Elena the risk she's taking with the witches' power. She swears him to silence.
Dana (Anna Enger Ritch) interrupts Bonnie and Elena at lunch and tells them a super hot boy wants to see Elena at the dance tonight. His name is Klaus. She's been compelled and that's all she knows.
Back at the house, Alaric knocks and then lets himself in. They brainstorm. Bonnie says -- in front of Klaus -- that if they can find him, she can kill him.
Damon tries her out, rushing at her. She flings him back. She says she can kill Klaus. Klaus inside Alaric takes note.
Klaus returns to Katherine, whose thigh is all blooded. He tells his witch Maddox (Gino Anthony Pesi) they're going to have to kill Bonnie.
Maddox says he can't take out Bonnie because she'll sense him coming. He also says channeling that much power will kill Bonnie -- Klaus just has to make her use it.
Maddox can toughen up Ric's body to withstand Bonnie's powers until using them kills her.
Caroline models her Jackie O costume for her mom, who tries to act natural. Matt picks her up.
Elena and Stefan get ready for the dance. He reassures her that they'll get Klaus.
At the dance, Klaus works his way through the crowd until he finds a kid named Chad and offers him extra credit.
Outside the dance, Jeremy tries to give Bonnie his ring, but she says it won't work on her. She thinks she's strong enough.
Inside at the dance, a girl announces a special shout out for Elena from Klaus. They look around for him, Bonnie takes Jeremy to dance. Stefan sees Caroline arrives and goes to warn her. Damon keeps Elena occupied on the dance floor.
Stefan tells Caroline what's up. Damon goes to talk to Bonnie. He heard her say she has a 50-50 chance of dying.
Elena notices Jeremy fuming at Bonnie, but he won't tell her what it's about.
Jeremy walks off and Stefan follows. Jeremy tells him about the risk Bonnie's taking.
Moments later, Elena confronts Bonnie and Stefan confronts Damon for keeping the secret.
In the hall, Chad and his friends gang up on Jeremy and start beating the crap out of him. Damon and Stefan interrupt and one of the kids shoots a crossbow at Damon. But Stefan realizes it's a distraction and tells Damon to find Elena.
Outside, Alaric/Klaus races up to Bonnie and Elena and tells them Klaus has Jeremy. They follow down the hall and then realize something is up. But by then they're away from everyone. Elena asks Alaric if he's on vervane. She thinks he's being compelled. He tells them he's not Alaric.
She realizes it's Klaus. He tells Elena she's not on his hit list tonight, but Bonnie is. He runs at her and she flings him back. He mentions he knows a witch, too. She throws him against the wall, but he gets right back up again. She's already weakened.
They run. Damon finds them. He sends Elena to find Stefan. Bonnie says she can't kill Alaric because Klaus will just possess someone else. She realizes Klaus is trying to kill her. Damon asks if she's willing to do whatever it takes to kill Klaus. She is.
Elena runs into Caroline on the dance floor but doesn't tell her what's wrong.
Bonnie struts down the hall on a Klaus hunt. He's waiting for her with a knife. She breaks his hand with her powers, then dislocates his shoulder. She tells him Alaric would want him to suffer. She gets a bloody nose.
Stefan and Elena find Damon and he tells them Bonnie is doing what she has to do.
Bonnie continues torturing Alaric as she keeps bleeding. She slams the door on Elena and Stefan when they run up. The lights spark and papers whirl everywhere in a dramatic flash of lights and power. Alaric stands up and suddenly the light show stops. Bonnie crumples to the ground. Klaus disappears.
Elena runs to Bonnie, lying on the ground, and bursts into tears. She can't find a pulse. Stefan can't help her. Bonnie's gone. Damon joins them and tells Stefan to get Elena home while he deals with Bonnie's body.
Damon puts Bonnie's body in his trunk. Jeremy runs up, not knowing what's going on.
Back at the house, Elena is in shock. Damon comes home and she confronts him, asking about Bonnie's body. She slaps him. "You need to listen to me, and prepare for what I'm about to say," he says.
Cut to Bonnie's body on the floor of the old witch house with candles around it. Jeremy checks on her.
Damon says Bonnie had to die because Klaus wasn't going to stop until Bonnie was dead -- and he had to believe it. As he explains, we see Bonnie open her eyes. Jeremy hugs her.
Damon tells her Bonnie cast a spell. She's OK.
Stefan follows Damon, saying he could have told him. Damon says he would have blabbed to Elena. Damon says he's willing to be the bad guy while Stefan worries about everyone's feelings, but at the end of the day, Damon will be the one to keep Elena alive.
Jeremy keeps Bonnie company. Bonnie asks Jeremy to tell Elena she's sorry. Jeremy opens a video chat so they can talk.
Back at the house, Elena tells Damon she understands why he did what he did. She wants to make sure Bonnie doesn't die for her. He thinks it might be the only way. Damon tells her if it comes down to her and Bonnie again, he'll let Bonnie die. "I will always choose you," Damon says.
Elena walks down the cellar where Elijah (Daniel Gillies) is still lying dead with the white ash dagger in his chest. She takes it out and waits.