Previously on 'The Vampire Diaries,' we learned that Damon was a former Augustine vampire... and that Dr. Maxfield has dragged him back into his creepy experiments.

Get out your poodle skirts and leather jackets -- we're in 1953. Welcome to Damon's flashback. Damon heads to his home in Mystic Falls, where he is promptly attacked by his Uncle and sold to the Augustine organization for some vampire testing (Damon has terrible luck with family).

In the present day, Katherine has taken up the therapeutic process of journaling at Stefan's request. (She isn't as fond of the process as her doppelganger Elena is.) Stefan is keeping Katherine on suicide watch, but Katherine quickly points out that Stefan isn't exactly in the right frame of mind to be keeping anyone else safe -- he's still having Silas-induced panic attacks. Luckily, Caroline is there to be Stefan's “sober sponsor." And Caroline has brought Stefan a gift -- the safe that he suffered in all of last summer.

Aaron heads to Elena's dorm to tell her some grim news: He was just informed that Jesse has committed suicide. Little does Aaron know that Elena is actually the reason for Jesse's demise. Elena asks Aaron to help her find Dr. Maxfield and Damon -- they have been missing for days. Elena drops a truth bomb on Aaron: Aaron's friend, Meagan, didn't commit suicide -- she was murdered, and Dr. Maxfield covered it up. She alludes to the fact that Jesse's death may also have been foul play, but, of course, skips out on all of those troublesome details.

In the present day, Damon is now under Dr. Maxfield's watch. He tells him the story of his past with Dr. Whitmore -- the original Augustine doctor. If you thought that Dr. Maxfield was harsh, think again. Dr. Whitmore tried to remove Damon's organs to see if they would grow back and even cut out parts of his eyes. Ouch. In more disturbing news, it seems that Elena's own father was a member of this vamp-torturing society.

Aaron lets Elena in on a little secret of his own: His name is actually Aaron Whitmore, and he owns the Whitmore house, allowing him to invite Elena inside. Aaron takes Elena to the house, where they have a run into Dr. Maxfield. In true evil doctor fashion, Dr. Maxfield sticks Elena with vervane, knocking her out. While Aaron is freaking out about Dr. Maxfield kidnapping his only friend at college, Dr. Maxfield lets him in on what he really studies: vampires. Dr. Whitmore, Aaron's father, trained Dr. Maxfield to torture -- er, study -- vampires.

Dr. Maxfield throws Elena in the cell next to Damon, who tells her all about the horrors he dealt with as an Augustine vampire. Damon spent five years being poked and prodded at by Dr. Whitmore. Thankfully, Damon made a friend, Enzo, a former World War II soldier. Enzo taught Damon to live in the future and to wait for revenge. Enzo's friendship gave Damon a reason to hang on to his humanity.

Damon tells Elena about the one time a year that the Augustine doctors allowed the vampires out of their cells. Dr. Whitmore let Damon and his friends out on New Year's Eve so that the guests could see Dr. Whitmore's “excellent work” -- the vampires he preyed on. The party gave Enzo an idea: Give Damon double doses of blood for a year so that Damon can build up his strength and escape during the New Year's Eve party the following year. When Dr. Whitmore releases Damon at the party (so his guests can “toast” with vampire blood) Damon goes full-on Ripper, eats a bunch of guests, and sets the place on fire. When it's time to release Enzo, though, Damon can't get his cell open in time and leaves his friend to burn. In that moment, Damon turns off his emotions.

At the Salvatore mansion, Caroline locks Stefan into the Pierce & Franklin safe. Katherine tells Caroline that Stefan won't save himself, but he will save someone else -- he's got a real “hero” complex, that one. Katherine sneaks into Stefan's safe and cuddles up with him and talks him down from the ledge... well, if “talk him down” really means talking about Damon and Elena's relationship. Katherine tells Stefan that the physical pain from the safe isn't the problem -- it's his heartbreak over Elena's relationship with Damon.

Back at Whitmore House, Dr. Maxfield finally gives Aaron his “birthday present": the packet of information about Aaron's parent's deaths. Dr. Maxfield tells Aaron to join him in his fight against vampires. In response, Aaron punches him in the face.

Aaron heads down to the cell, gun in hand. He points the gun at Elena -- he thinks that she killed her roommate, Meagan, and his parents. But Damon tells Aaron that it wasn't Elena who killed his parents -- it was Damon. It was all part of his plan for revenge against the Whitmore family. Damon's plan for vengeance was to kill every member of the Whitmore family with the exception of one per generation. That included Aaron's parents and his Aunt Sarah. Elena demands to know when Damon killed his latest Whitmore victim. Damon admits that he killed Sarah only a few months ago, when Damon and Elena were very much together. Aaron shoots Damon (which, we hate to admit, he kind of deserved).

In the Salvatore mansion, Stefan thanks Katherine for all of her help. She tells Stefan that she doesn't always know what she's doing, but she's glad she helped -- which leads to the former couple kissing passionately by the fire.

Damon wakes up from his gunshot wound. When he looks for Elena in the next cell over, he finds that she is gone. When Elena wakes, we find that she is on Dr. Maxfield's table once again. Laying on the board next to her is Damon's former good buddy, Enzo -- very much alive.