June 11, 1953 Damon drops in on Joe at the house. Joe sent for both of them. The brothers haven't spoken since Damon left Stefan on the train platform in WWII. Joe stabs Damon with a vervane needle, saying the money was too good to pass up. Damon manages to stab Joe in the neck with his broken glass before he drops. Another man comes in and says he'll be Damon's doctor from now on.In the present, Damon wakes up in a cell with Wes Maxfield injecting him with vervane. He tells Damon that because he killed their test subject last night (Jesse), Damon's going to take his place.
At the house, Stefan keeps watch over Katherine, trying to ensure she doesn't kill herself. She's pouty and angry about his hovering and thinks he can't help her until he deals with his own PTSD. She called in help. Caroline arrives as his sober coach -- with a giant safe.
At college, Elena drops in on Aaron, who is reeling over the death of his roommate, Jesse. Even though Elena killed him, she pretends to be shocked. Aaron is overwhelmed by the fact that someone else close to him died.She asks about Wes, who became his legal guardian after his aunt Sarah died. She tells Aaron that Damon went to talk to Wes last night and no one has seen either of them since. She asks for his help finding Wes. Aaron thinks he knows a place.
Wes checks in on Damon in his cell.Damon remembers the last time he was locked up, by Dr. Whitmore. Flash back to 1953, Whitmore has Damon strapped to a table. He plans to experiment on him, knowing that as a vampire he'll heal from all his wounds. He plans to cut out parts of Damon's internal organs so he'll regrow them. To begin, he stabs Damon in the eye.Maxfield tells Damon that after training Jesse to crave vampire blood, he's ready to take his research to his next level.
On campus, Elena asks Aaron if he thinks it's weird that both his friends committed suicide in their first semester. Elena tells Aaron that Wes covered up Megan's murder. Aaron wants to find Wes to ask him about it.He takes Elena to the Whitmore House, which she knows she can't enter. But Wes invites her in and she's able to enter. He confesses that he owns the house as part of the Whitmore Trust he inherited when his parents died. His name's Aaron Whitmore.Elena looks at a picture and recognizes her father. Wes joins them, and says Grayson Gilbert was one of the best doctors the Augustines ever had. Then he injects Elena with vervane.
Back at the house, Stefan questions whether the safe is a good idea for coping with his PTSD.
Back at Whitmore, Aaron struggles to understand what Wes is doing. Wes tells him vampires exist and Elena is one of them. He opens his safe to reveal stacks of Whitmore files. Wes explains to Aaron that his father taught him everything he knows about vampires and research and the Whitmore Trust has been funding his research. He tells Aaron it's his legacy.Elena wakes up in a cell next to Damon. Damon confesses he's been there before and tells her about Whitmore's torture, including cutting up pieces of them every day. He was there for about five years. He made a friend, Enzo, a soldier in Europe during WWII, who was also a vampire. Whitmore was working in a battlefield hospital overseas when he discovered Enzo was a vampire and locked him in a coffin and shipped him overseas. He'd been locked up ten years.Enzo tried to teach Damon how to survive, including picturing exactly how he'd get his revenge.Elena tells Damon that her dad worked with Whitmore and was an Augustine. She doesn't want to believe he'd be part of a place that would cut Damon's eyes out.
Back in Mystic Falls, Caroline reads up on PTSD while Stefan is in the safe. She's oblivious as Stefan starts to freak out inside. Outside, Katherine wonders how you help the guy who is always the hero for everyone else. She gets an idea.
1953 Enzo keeps Damon going by talking to him about a girl named Maggie that he liked. Whitmore interrupts, asking who's next. He goes for Damon, but Enzo volunteers. Damon listens to him scream from in his cell until he's finally brought back in a bloody heap. Damon asks Whitmore why he's doing this and he explains he's trying to understand vampires on a cellular level to make use of them. Back in the present, Elena thinks Stefan will figure it out and come rescue them, but Damon never told him he was locked up -- he didn't want to give him more to feel guilty about. Damon explains how he escaped. They let the vampires out once a year for the Augustine's New Year's Eve party to show them off. They were weak from vervane and captivity. Whitmore demonstrates vampire blood's healing powers, using Mrs. Fell as a volunteer. She drinks vampire blood to heal her hand after he cuts it. Enzo comes up with a plan, suggesting one of them drink both of their daily rations of blood for a year so that when they're let out next New Year's Eve, one of them will have the strength to fight. They play rock paper scissors and Damon wins. Elena wants to know what happened, but Damon is not forthcoming with the details, saying only that it wasn't pretty.
Wes gives Aaron his grandfather's watch, which he says is a precaution against vampires. Aaron sees news clips about his parents' death at a campground. Wes admits they were killed by vampires. Aaron decks Wes, knocking him to the ground. He takes the gun and bullets from the safe and the watch.
Back in the safe, Stefan wakes up next to Katherine. She knows he gets anxious and violent when his PTSD kicks in. She also knows he wants to keep her alive, so she's counting on him not hurting her.
Down in the cell, Elena prods Damon to tell her how he escaped. In 1958, he'd been drinking Enzo's rations for a year and he'd gotten stronger. When Whitmore opened the cage to take Damon out to show him off to the guests on New Year's, Damon broke his own hand to slip out of the chains. He gouged Whitmore's eyes out, then attacked as many people as he could in the room, knocking over a candelabra as he went. The fire raged with Enzo still in the cage. Damon tried to free him, but the bars were coated in vervane and the fire was advancing. Finally, he chose to save himself, but he turned off his emotions first so he could leave Enzo behind. He left Enzo there to die in the fire.
Back at the house, in the safe Stefan hyperventilates, saying he feels like he's dying. Katherine tells Stefan she believes there is something to the doppelganger prophecy and Stefan wants to get far away from Damon and Elena and she's just the latest excuse to stay in town. Stefan starts choking her. She tells him she thinks he's choosing to focus on the physical pain of drowning in the safe instead of the emotional pain of Elena breaking his heart. She turns to offer Stefan her neck and urges him to fight it. She promises she's there with him. They are dangerously close to kissing when Caroline opens the safe, worried about how quiet it got. Out of the safe, Stefan seems to look at Katherine differently.
Aaron comes down to the cells in the basement with his gun. He accuses Elena of killing Megan and possibly of killing his parents. Damon stops him, and says it was him. Damon explains that with Enzo dead, he had to carry out his revenge plan himself. He planned to kill all the Whitmores in a generation, except one, then let him grow up and start a family, and then kill all of them except one, and so on. And he did. Elena is disgusted and asks when the last one was. A few months ago, Sarah in Charleston. It was a weekend trip. Elena realizes they were together then. Aaron shoots Damon.
Back at the house, Stefan tells Katherine he was right. He admits she knew what she was doing, and she admits sometimes she doesn't even know. She slides up close to him and runs her hands across his chest. She kisses him. He kisses her back. Caroline leaves Elena a message, saying she's going to stay at her mom's. She hears Stefan and Katherine making out and tells her to call.
Back in his dorm room, Aaron calls Wes, angry about having been lied to his whole life. Wes tells him to live his life. Damon wakes up from his head wound in his cell. Elena is gone. Elena wakes up strapped to an exam table next to another vampire. He introduces himself. "My name is Enzo," he says.