After a twisted plan left the life of his girlfriend Elena linked to that of his best friend Bonnie, Damon is forced to navigate his new reality without the love of his life. A newly empowered Bonnie has decided that she will be Damon's moral compass and keeps a close eye on him as he, in turn, cautiously keeps tabs on Alaric, following the loss of his fiancée Jo. Meanwhile, as he waits for Caroline to sort out her emotions, Stefan takes an active role in protecting the town from Lily and her family of Heretics, who have wasted no time wreaking havoc in Mystic Falls.

Elsewhere, Enzo struggles to find his place in Lily's new life, and is quickly forced to decide where his true loyalties lie. Finally, with the stakes higher than ever, Matt, who has recently completed his deputy training program, teams up with Stefan and Caroline to put a stop to the Heretics, but an unexpected turn of events leaves one of them in a dangerous position.

When an impulsive decision by Damon threatens to unravel a carefully negotiated deal between Stefan and Lily, he has no choice but to make amends with his mother before things spiral further out of control. However, Lily remains one step ahead and carries out a harsh plan that hits Damon where it hurts most.

Elsewhere, after returning to Whitmore Collage, Alaric turns to Bonnie for help with a mysterious and potentially dangerous artifact he has obtained, while Matt is forced into making a risky life or death decision. Meanwhile, Caroline, who finds herself a pawn in Lily and the heretics' plan for retribution, uncovers a shocking detail about Stefan's past.

In the aftermath of a clever plan orchestrated by Lily, Damon sets off on a road trip with Bonnie and Alaric in search of leverage they can use against his mother. Meanwhile, Caroline, who is being held hostage by the Heretics, learns some shocking information about Valerie’s past, while Stefan learns a few unexpected details about his own past from Lily. Finally, Alaric turns to Bonnie for her help after coming clean about a secret he’s been keeping.

Just as Damon thinks he's gained the upper hand in his fight against Lily, an unexpected turn of events leaves him scrambling for a plan B. Elsewhere, when the fallout of Damon's actions gains the unwanted attention of Mary Louise and Nora, Stefan and Caroline are forced to spend the night distracting the girls at Whitmore College's Heaven & Hell ball. Finally, after suspecting that she's up to something, Enzo sets off on a mission to find out what Valerie is hiding, while a plan set by Alaric and Bonnie leaves their worlds turned upside down.

After realizing the downward spiral he was on, Damon decides he’s going to turn over a new leaf and that his actions moving forward will do right by Elena. Lily prepares for the arrival of a special figure from her past, while Enzo stands by not sure what to expect.

Elsewhere, at Caroline’s urging, Stefan comes face-to-face with Valerie and learns some upsetting details about her past, while Enzo and Bonnie find themselves at odds when they’re forced to fend off a violent threat. Finally, when Bonnie learns some disturbing information involving the Phoenix stone, she is forced to confront Alaric.

After being reunited with her former love Julian, Lily hosts a dinner party to introduce him to Damon and Stefan and to declare peace between her family of Heretics and the residents of Mystic Falls. Damon and Stefan find themselves at an impasse when they realize they have differing views on how to handle Julian's arrival. At the party, Bonnie and Matt uncover a strange mystery involving some unsuspecting residents, while a devastating revelation causes Alaric to reach his breaking point.

In order to get through to Lily about Julian's manipulating ways, Stefan and Damon confront their mother with painful memories from their childhood. However, when Lily reveals a dark secret she's been harboring for over 160 years, Stefan and Damon are left questioning everything they've ever known about their family. Determined to prove himself to Lily, Enzo comes face-to-face with Julian and challenges him to a duel, but an unexpected twist threatens to complicate things.

Elsewhere, Matt finds himself in the middle of a deepening mystery involving the residents of Mystic Falls, and Caroline's world is turned upside down when Valerie reveals some life-changing news to her.

As Julian and Lily throw a party to celebrate Mary Louise and Nora's anniversary, Stefan and Damon set in motion a risky plan to eliminate a new threat posed by Julian. Meanwhile, following a major revelation uncovered by Valerie, Caroline is forced to face her new reality, even as it threatens to destroy her relationship with Stefan. Finally, determined to do what's best for her family, Lily makes the most difficult decision of her life.

With the holidays in full swing, a search for Julian leads Damon and Stefan to a small town outside of Mystic Falls. While managing a holiday toy drive at Whitmore College, Bonnie seeks help from Nora and the two strike up an unlikely friendship.

Elsewhere, Caroline does her best to navigate her new life as a pregnant vampire, while Alaric grows concerned that the pregnancy is effecting her more than she's letting on. Finally, after finding himself at odds with Damon, Stefan is forced to take matters into his own hands, setting off a tragic chain of events that leaves their lives changed forever.

After finding himself on the wrong end of Julian's plan to avenge Lily's death, Damon awakens to find himself trapped inside the Phoenix stone, tormented by a traumatic experience from his time in the Civil War and forced to face his darkest demon in order to get out. On the outside, Bonnie is in a race against the clock to get Damon out before the effects of the Phoenix stone take over and leave him changed forever.