Months after Damon and Enzo mysteriously vanished from the Armory vault, Stefan tirelessly pushes forward with their search, while Bonnie struggles holding onto hope that they will be found. Meanwhile, a dangerous encounter with an unexpected visitor leaves Caroline and Alaric fearing that someone - or something - may be targeting their family. Finally, after following some mysterious clues, Stefan realizes that whatever has a hold of his brother may have a more damaging grip over him than he could have ever imagined.
After learning that someone from Stefan's past may be Damon and Enzo's next target, Stefan, Bonnie and Caroline head to North Carolina. There, Bonnie takes drastic measures in an attempt to break Enzo free of whatever has a hold over him. At the Armory, Alaric and Georgie stumble upon a mysterious symbol that may be related to the supernatural force controlling Damon and Enzo. Finally, Caroline gets an unexpected surprise from Stefan.
As Enzo continues to fight the control over him, Bonnie finds herself at the center of a deadly game and forced to make a heart wrenching decision involving two of the most important people in her life. At the Armory, Alaric researches a mysterious artifact that he hopes will help in their fight to get Damon and Enzo back. Finally, Damon's downward spiral leads him to Tyler Lockwood who attempts to talk some sense into him before it's too late.
Tasked with finding a mysterious artifact, Damon's latest mission takes him to Texas where a unhappy run-in with Peter Maxwell leads to a surprising revelation. Meanwhile, after gaining the upper hand in their fight to save Damon and Enzo, Stefan and Alaric team up and uncover the origins of the mysterious force they're up against. Finally, Matt returns to the fray after his past and present collide in an unexpected way.
Spiraling down a dangerous path of self-destruction, Damon's latest actions prove he may be beyond the point of return. Unwilling to give up on his brother, Stefan is forced to make a gut-wrenching decision that threatens to change their relationship forever. Elsewhere, Bonnie gets advice from Caroline on how to break through to Enzo, while Matt attempts to decipher a mysterious box of messages that he's received. Finally, after tragedy strikes close to home, Stefan and the others are forced to remember what matters most to them.
When her children become the focus of the Siren's latest plan, Caroline takes drastic measures to ensure nothing gets in the way of keeping her family safe. In a race against the clock, Stefan pledges to do everything he can to save the twins, while tensions between Alaric and Caroline boil over, leading them to face some harsh realities about the future of their family. Meanwhile, when Enzo finds himself unable to fight off Sybil's latest move, Stefan dives into his subconscious and along the way, sets off a chain of events that leaves him faced with a life-changing decision.
Faced with the fallout from his interaction with Cade, Stefan is determined to have one thing go right - Christmas Eve with Caroline. However, when Damon and Sybil crash their Christmas Eve dinner, which had been joined by Alaric, Matt and Peter, things quickly take a dark and twisted turn. Meanwhile, in a series of flashbacks to Stefan's past, Cade's attempt to entice him with his mysterious agenda leaves Stefan faced with an unimaginable decision.
Stefan and Damon attend an anger management support group looking for their next victim. Sybil is still alive and teaching a group of high school students who she'll later use as leverage to get Caroline to locate a historical artifact that can be used against her. Meanwhile, Stefan and Damon continue their commitment to Cade as they test the morals of a young doctor, Tara.
Stefan and Damon return to Mystic Falls at Sybil's request as she is still in search of the historical artifact. Bonnie returns from Paris wearing a vile of Enzo's blood making Caroline, wonder if she will become a vampire. Stefan, Damon, Caroline, Bonnie and Enzo all attend the Miss Mystic Falls pageant where Sybil continues to taunt Damon with memories of Elena.
Sybil enacts revenge on Damon by putting him in a catatonic state. Caroline and Bonnie enter Damon's mind and run into familiar faces from the past, only to discover Stefan is the key to Damon's fate. It's a race against time for the bell as both Sybil and her sister Seline jockey for its control.
Cade returns to Mystic Falls and presents Damon and Stefan with additional assignments, each with unthinkable consequences. Even with tension growing in their friendship, Caroline and Matt do their best to protect the town's residents from Cade's appetite for their souls. Bonnie and Enzo hit the road on a romantic trip, taking the bell with them in hopes to keep it safe.
In order to save Stefan's soul, Damon makes a deal with Cade to retrieve the Maxwell journal. Alaric and Matt refuse to hand the journal over as it may contain the key to destroying Cade. Caroline desperately tries to connect with Stefan before Cade goes through with his plan.
Damon and Alaric come face to face with an old enemy after they obtain a weapon that may be able to destroy Cade. Stefan is held captive by a surprising acquaintance and is forced to confront a dark secret from his past. Meanwhile, Caroline and Matt try to keep Stefan's unhappy history from destroying him. Cade focuses his attention on Bonnie and digs deep into her mind.
Damon and Stefan must join forces against Cade in order to save Elena's casket. Meanwhile, Caroline and Alaric deal with their daughters' burgeoning magical powers.
A wedding is quickly planned in order for Damon and Stefan to lure a dangerous enemy out into the open. This looming threat puts the fate of Mystic Falls in eminent danger and must be destroyed.
With the fate of Mystic Falls at stake, Stefan and Damon must fight their greatest enemy for one last battle.