The episode opens with Klaus, who is still possessing Alaric, checking his knowledge of Mystic Falls and the residents by forcing Katherine
to tell him everything that she knows. She confirms that the dagger is in Elijah
, who is in the Salvatores' basement and reminds him that Jenna is angry with Alaric. Klaus asks her what else she knows, but Katherine says she has told him everything and begs him just to kill her now. Klaus suggests that Katherine might not know everything and compels her to tell him what the others could be keeping from her. Katherine reveals that they were trying to see if Bonnie could kill an original without the dagger, but admits that she doesn't know if Bonnie has her powers back. Again, she asks him to kill her, but Klaus tells her that he has searched for her for 500 years and will make her death last at least half that long. He hands her a knife and tells her to stab herself in the leg. She does, and Klaus tells her that he wants her to do it over and over again while he is out. He leaves to find Elena. As he leaves, Katherine stabs herself again.
Elena signs the paperwork to take control of the Salvatore home as a safehouse. Outside, Damon asks if Bonnie can take on Klaus and Stefan explains that she thinks she can channel enough witches' power to do it. The pair wonder if Klaus has killed Katherine. They go to get into the house, but as Elena now owns it, she has control. She invites Stefan inside, but refuses to let Damon in until he agrees to play by Elena's rules. Eventually he gets in, but Stefan and Damon are shocked to see Elena and Bonnie are leaving for school. Elena points out that she doesn't want to be a prisoner and adds that she has Bonnie to protect her. Stefan decides to go with them.
Matt arrives, flustered, at Caroline's house and meets Sheriff Forbes. He explains that he is worried about lying to Caroline, who wants to go to the school's 1960s dance with him. Sheriff Forbes begs him to pretend he doesn't know anything. She explains that she needs time to come to terms with what she has just found out. Matt reluctantly agrees. At school, Elena finds a poster for the 60's dance but Stefan shakes his head. She shows it to Bonnie, who nods and smiles. Klaus arrives to take the lesson, which is about the 1960s. He spots Elena, who corrects him when he claims Watergate was in the 1960s. Meanwhile, Caroline is preparing for the dance when Matt arrives and kisses her, agreeing to take her to the event. At lunch, Bonnie bans Jeremy from telling Elena that killing Klaus would kill her as well. She insists that she will go through with it. Elena arrives and Jeremy storms off angrily. Elena's friend Dana arrives and reveals that a "hot guy" has just asked her if Elena is going to the dance. She reveals that his name is Klaus. Elena and Bonnie are shocked and Bonnie asks if Klaus is in the room. Dana says she doesn't know and Bonnie realizes that she is compelled. Dana explains that Klaus wants Elena to save him the last dance.
Back at the Salvatore house, Damon suggests that they will have to go to the dance and find Klaus. Klaus arrives, still disguised as Alaric, and discovers that Damon wants to be a chaperone because Klaus has made a move. Bonnie points out that Klaus has no idea how much power she can channel and suggests she can kill him. Damon is unsure, but Bonnie shows how much power she has by throwing him across the room. Klaus watches on and later returns to Alaric's house. He finds his warlock, Maddox, and asks him to take out Bonnie, but Maddox explains that Bonnie has too much power and he won't be able to get near her. Klaus claims that Alaric's body isn't good enough for him to kill her, but Maddox suggests that he can cast a spell to make Klaus stronger. He adds that channeling that much power would kill Bonnie and says Klaus just needs to provoke her.
Meanwhile, Caroline gets ready for the dance and Sheriff Forbes looks on sadly, claiming that she is just stressed because of work. Matt arrives, and exchanges a meaningful glance with Sheriff Forbes before taking Caroline out. Meanwhile, Elena chooses a dress for the dance, but Stefan realizes that she is worried and says they can still back out. Elena admits that she had convinced herself Klaus wasn't real, but he is. Stefan promises they will put an end to him that night.
At the dance, Klaus arrives and looks across the room. He meets Dana and asks her date, Chad, if he would like to earn "a little extra credit". Outside, Jeremy hands Bonnie his ring to protect her, but Bonnie points out that it won't work because she is supernatural herself. She tells him that the witches' warning doesn't mean she will die. Jeremy points out that he doesn't have much luck with girlfriends, but Bonnie tells him that she feels strong and can do this. Damon appears, followed by Elena and Stefan. They head inside, but are shocked when Dana reads out a shout out - for Elena from Klaus. Elena worries that she knows everyone here and Damon suggests that Klaus might just want them to think he's at the dance. He tells everyone to blend in and goes to see Alaric - or Klaus. Klaus claims that the shout out was a "little twisted", but Damon dismisses it and Klaus appears surprised. Meanwhile, Elena sees Caroline arrive and wants to warn her. Stefan offers to do it and hands Elena over to Damon. Elena and Damon dance together, and Stefan goes to update Caroline. Later, Damon finds Bonnie and reveals that he heard her talking to Jeremy. As they dance, Bonnie confirms that she could die, but would sacrifice herself for Elena. She tells him not to tell Elena and Damon agrees. He asks if there's any way for Bonnie to improve her chances of survival and she jokes that she might start to think he cares if he's not careful. Meanwhile, Elena wonders what Bonnie and Damon are talking about, but Jeremy storms off. Stefan follows him and Jeremy admits that Bonnie could die. He admits that he doesn't know what to do because he wants to save Elena as well. Stefan tells Elena and goes to see Damon, accusing him of keeping secrets. Meanwhile, Elena pulls Bonnie outside and refuses to let her sacrifice herself. However, Bonnie points out that Elena would also do it for her.
Jeremy walks down the school corridor, but is confronted by Chad and his friends, who start a fight. When Damon and Stefan arrive, one of the boys stakes Damon with one of Alaric's vampire-slaying weapons. Damon pulls out the stake and rushes to the boy, but Stefan tells him they are just compelled and suggests that Klaus is staging a distraction. Damon rushes off to find Bonnie and Elena. Meanwhile, 'Alaric' tells Bonnie and Elena that Klaus has Jeremy and leads them down a corridor. Elena worries that something's not right and Klaus eventually confirms that he is not Alaric. He tells Elena that she is not on his hit list that night, but Bonnie is. Bonnie uses her power to throw him across the corridor, but Klaus tells her that if she kills Alaric's body, he'll just find another. Bonnie and Elena run away and Bonnie uses her powers to shut the doors behind them. They meet Damon and explain that Alaric is being possessed by Klaus. Elena runs to find Stefan. Damon tells Bonnie to kill Klaus, but Bonnie admits that he is protected by a spell. She explains that Klaus knows about her powers and is trying to kill her. Damon says Klaus will not get to win tonight and asks if she's still willing to do whatever it takes to kill him.
Elena runs into the dance looking for Stefan, but Caroline claims to Matt it's just the "same old drama". Meanwhile, Bonnie finds Klaus, who is sitting with a dagger. He asks if she wants to do this the easy way or the hard way, but Bonnie uses her powers to hurt him. However, the power also gives Bonnie a nosebleed. Elena and Stefan find Damon, who reveals that Bonnie is "doing what she has to do". Stefan asks where she is and Elena runs to find her. They discover Bonnie in a room with Klaus - the lights are flashing, her nose is bleeding and sparks are flying. Elena and Stefan try to run in, but Bonnie slams the doors in their faces. Bonnie and Elena stare at each other and suddenly Bonnie jerks and collapses on the floor. Klaus disappears and Elena runs in, discovering that Bonnie has no pulse. She sobs and Damon arrives, telling Stefan to take Elena away so he can "deal with the body". Elena is furious at his insensitivity, yelling that it is Bonnie he is talking about. Damon tells Stefan to get Elena home now and says he will find Jeremy. Later, Damon puts Bonnie's body in his car and Jeremy approaches, asking where Bonnie is. Damon explains that they need to talk.
Back at the Salvatore house, Elena sobs and claims that Bonnie's death is her fault. Stefan insists that it was Klaus. Damon arrives and Elena shouts at him, saying he knew Bonnie would die. When Damon admits that he did, Elena slaps him. However, Damon tells her that she needs to listen to him now. He explains that Bonnie had to die - Klaus wasn't going to stop until he knew she was dead. He adds: "He had to believe it." Meanwhile, Jeremy goes to visit Bonnie's body in a tomb surrounded by candles. Bonnie suddenly wakes up and Jeremy hugs her. Back at the Salvatore house, Damon explains that Bonnie cast a spell to protect herself and is fine. He walks off and Stefan follows, saying Damon should have told him. However, Damon points out that Stefan would have told Elena. Stefan complains that Damon has put Elena through a lot of pain, but Damon says that's why he didn't tell Stefan. He says he doesn't mind being the bad guy who has to make the life and death decisions. He says he will even let Elena hate him for it because at the end of the day, he will be the one who keeps her alive.
Back in the tomb, Bonnie explains that she is sure she is safe there. Jeremy produces a laptop and wireless internet and sets it up so that Bonnie can talk to Elena over a webcam. Bonnie sobs that she is sorry as she didn't have time to tell her what was happening, but Elena forgives her and says she just needed to see Bonnie's face to know she is okay. Later, Elena goes to see Damon and explains that she understands why he did what he did. However, she adds that she will not let Bonnie die for her and suggests that they can find another way. She apologizes for hitting him. Damon replies that if it came down to Elena and Bonnie, he would gladly let Bonnie die. "I will always choose you," he says.
The episode ends with Elena saying goodnight to Damon and slipping down to the cellar without his knowledge. She looks at Elijah's body and pulls the dagger out of his chest.