Back during the first half of Season 2 [season 2 refresher here] we learned that Elena - the doppelganger - is the key to breaking the Sun-and-Moon spell (you know, the one that keeps most vampires from going out during the day and makes werewolves turn only during the full moon) so the oldest vampire in the history of time, Klaus, is looking for her so he can kill her. One of the original vampires, Elijah has offered to keep Elena safe from Klaus, as long as she plays by his rules so he freed Stefan from the tomb, while Katherine is still stuck in there. Meanwhile Caroline helped Tyler get through his first full moon werewolf transition. Mason Lockwood is dead and his werewolf friend Jules has come to town. She took a big bite out of Rose's shoulder (she was trying to get to Damon) and since werewolf bites are fatal to vampires, she's slowly dying.
Stefan is trying to build up a tolerance to vervaine, just like Katherine did and while Elena is happy to have him back from the tomb, he can't help but keep worrying like the angsty teenager vampire that he is. He wants to get answers from Isobel, Elena's biological mother who was an expert on werewolves and vampires (before becoming one of the latter). Damon wants answers too because Rose's werewolf bite is looking mighty infected and she's slowly dying from it unless they can figure out a cure. They both think Isobel could help and even though Alaric tells them not to trust her, he gives he the last contact number he had for her.
Damon is rightfully pissed at Jules and he offers to not kill her in exchange for info on how to cure a wolf bite, but she claims there's nothing he can do.
Jules: You want a cure? I'll tell you the only cure that exists. Take a stake and drive it through her heart.Damon leaves Elena to take care of Rose, whose health is quickly deteriorating.
Elena: You're not going to die.
Rose: Such a human thing to say.
Rose then apparently begins to lose her mind as well, mistaking Elena for Katerina (Katherine) and trying to kill her. Elena hilariously protects herself by pushing a dresser in front of the door... are you kidding me? That's going to keep a vampire out? Really? C'mon. Give us a break. I don't care how sick she is...
Rose runs away and shows up at the pep rally (or something? God, Mystic Falls is all about the supernatural creatures and the extra-curricular special events). She's puking behind a dumpster when a custodian tries to help her, so she kills him. Another person of color killed after 5 seconds on screen. What else is new? Don't worry, she shortly afterward kills a white couple too. Damn and Elena find her and she snaps out of it long enough to writhe in pain and beg Damon to just "make it stop". (Congrats to the makeup department for the work they did on Rose by the way... perfect combination of vampire and sick).
Tyler goes to Caroline's house... he can't believe that she risked death (if he had bitten her by accident) in order to help him. And then he plants one on her!
Caroline: Everyone just needs to stop kissing me!Damon psychically takes Rose to a meadow she enjoyed as a child (in a dreams that he compels, somehow) before giving her a mercy stake through the heart. Vampire euthanasia. Wait... was Damon crying? They keep showing us signs of his softer side... but of course, no good can come of this.
Elena: A friend usually knows when their friend is hurting.Jules finally talks to Tyler and tells him that she's a werewolf too and offers to help him. She also tells him that Mason was murdered and that Caroline and "her little vampire friends" were behind it.
Damon: What do yo wanna hear? That I cared about Rose? That I'm upset? Well I didn't and I'm not.
Elena: There you go, pretending to turn it off, pretending not to feel. Damon, you're so close, don't give up.
Damon: I feel Elena. Okay. And it sucks. What sucks even more is that it was supposed to me. Jules was coming after me.
Elena: You feel guilty.
Damon: That would be human of me, wouldn't it Elena, and I'm not human. You're one to talk about giving up. It's all you've done is give up. Go home. There's been enough doom, gloom and personal growth for one night.
Tyler: Who are you?Uh oh.
Jules: I'm your friend. There are others like us and they're on their way.
Meanwhile... Stefan couldn't find Isobel, but he found the next best (er, worst?) thing... Yep. Uncle Daddy is back! John Gilbert. Oh boy.
Mysteriously missing from this episode: Bonnie and Jeremy. Guess Elena and the Salvatores didn't need them to use them for anything. In my mind, I like to believe that they were off somewhere having sex.
The episode ends with Damon going through a downward spiral of existential crisis with an innocent
Jessica: I don't want any trouble.And then he kills her! Love you Damon... still love you Vampire Diaries.
Damon: Neither do I. But it's all I got is trouble. .... You are my existential crisis. Do I kill you or not kill you?
Jessica: Please don't.
Damon: But I have to, Jessica. Because I'm not human. And I miss it. I miss it more than anything in the world. That is my secret. But there's only so much hurt a man can take.
Jessica: Please don't.
Damon: Okay. You're free to go.