Before Sunset

Klaus acts on his intentions to leave town with Elena, but finds resistance from a surprising new enemy, Alaric the new Original vampire hunter. Bonnie calls on Abby to help her with a difficult spell that will stop Alaric's heart, the same desiccation spell Abby used on Mikael. Abby warns Bonnie that this will make her subject to temptation she might not be able to resist. Alaric forces Elena to come to the school after he captures and tortures Caroline and tries to persuade her to kill Caroline, as Elena had previously expressed her interest in killing vampires. When Elena tries unsuccessfully to save Caroline and is held captive by Alaric, the Salvatore brothers and Klaus rush to save her. Klaus reveals that it is his bloodline to which the Salvatore brothers and Caroline are linked. As Caroline is escaping, Klaus grabs her and makes sure that Caroline gets home safely. A stunned Caroline agrees to let Klaus, Damon and Stefan save Elena, thanks Klaus, and leaves. Klaus goes to save Elena, taking on Alaric, but Alaric quickly turns the tables and is ready to stake him, but just as Alaric is ready to kill Klaus, Elena correctly assumes that she is Alaric's lifeline and that if she dies, so does he. Klaus escapes with Elena, intending to bleed her dry before he leaves town because he wants to kill Alaric. Tyler, Stefan, and Damon use the desiccation spell on Klaus, "killing" him without killing Tyler. Damon and Stefan have a surprisingly candid conversation about the future: if Elena chooses one brother, the other leaves town. Alaric outs both the Sheriff and the Mayor in front of the Council for failing to protect the town from vampires as both their children are vampires. Elena collapses at the end of the episode.

Plot summary from Wikipedia (CC BY-SA 4.0). Source