The season begins with Damon and Enzo luring two unsuspecting young people to their eventual deaths. They have been tasked with finding the worst of humanity and serving them up to the master. They don't enjoy this task but can't stop themselves.
Stefan and Caroline are happy and the two of them and Bonnie take turns writing to Elena. They're all trying to find moments of happiness but Bonnie is struggling. While Stefan and Caroline have each other, she only has memories of her time with Enzo. As Caroline prepares for work, she and Stefan get news that a body has been found and believe it's a clue to Damon and Enzo's whereabouts.
Ric manages the Armory's excavation and learns that the walls in the cave can be passed through, but only if a person's hearing and vision are blocked completely. That's apparently how Damon and Enzo were able to leave the cave since there are no other exits. In the warehouse, Damon and Enzo debate about whose job it is to feed the beast. They discuss the merits of flipping off their humanity switches, which Damon says he's done. Enzo refuses.
Ric and his interns follow the tunnel to see where it leads. Caroline hangs out with the girls at work and tracks Virginia St. John, the daughter of the Armory's former management team. They believe she has answers as to what escaped from the vault. Ric and his interns find a vault at the end of the tunnel and ancient artifacts and gold beyond it.
Stefan uses compulsion on a detective and learns more about the girl Enzo killed. Bonnie picks up on clues leading straight to Enzo and Caroline helps lead them to a nearby slaughterhouse. At home, the nanny preps dinner for the girls when someone breaks into the house. Seline is on the phone with Caroline who rushes home after learning her girls are in danger. She finds Virginia St. John in her girls' bedroom.
Stefan, meanwhile, enters the slaughterhouse hoping to find Damon. He's in luck, but Damon doesn't want to leave. Or can't. He reveals that he and Enzo have been killing "bad" people and goes on to describe the Hell in which he's living. Then he tells Stefan that the monster doesn't want him. Yet.
Caroline sends the nanny and the girls out of the house so she can deal with their attacker: Virginia St. John. Whatever escaped from the vault needs or wants the twins. To keep from talking, Virginia bites off her own tongue and eventually dies.
Stefan continues pleading with Damon to leave but Damon refuses, citing his humanity-less existence as his reason. Stefan immobilizes Damon just as Bonnie arrives and demands they find Enzo before leaving. Enzo appears, punching Stefan in the face, and tells them to leave. Stefan listens to Enzo.
Ric and Caroline take care of Virginia's body and he suggests that he move in so that they can better protect the girls. Caroline objects and then realizes that Ric's plan involves Caroline moving in with Stefan.
Stefan takes Bonnie back to the cabin where they discuss the fact that Enzo and Damon aren't in control of themselves. She knows Enzo left clues behind so they would be found and takes it as a sign that he wants their help. Stefan can't shake the fact that he is responsible for Damon. As Bonnie sits inside alone, she puts together the clues.
Damon once again advises Enzo to flip his switch so that the monster will be unable to use what he cares about against him. As they drive their latest victim to his death, Damon dreams about the first time he met Elena and asks for her help hanging on.
Bonnie calls Alaric to figure out the clues Enzo left. Together they determine that they're dealing with a Siren.