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.

In order to lure a vengeful vampire hunter named Rayna Cruz away from his friends in Mystic Falls, Stefan heads to New Orleans, where Valerie has learned of a safe house that can protect him. Once there, he comes face to face with Klaus Mikaelson, who soon becomes suspicious of his old friend's unexpected arrival in his city. Meanwhile, Enzo, who is working on behalf of a mysterious organization called The Armory, approaches Damon and Bonnie with a plan that could protect Stefan from Rayna. Finally, after learning that Alaric has decided to leave for Dallas with the twins immediately, Caroline offers to accompany them on the trip and finds herself contemplating her own future in Mystic Falls. The crossover continues on The Originals S03E14 A Streetcar Named Desire (II).

When complications from her supernatural pregnancy leave Caroline's life hanging in the balance, Stefan and Valerie take extreme measures to try and save her and the babies. Meanwhile, after uncovering a dark secret about Damon, Enzo uses the information to force Damon into helping him track down Rayna Cruz, a ruthless vampire hunter who is on the loose. However, when Damon's actions inadvertently put everyone he loves in Rayna's path, he is forced to make things right before it's too late.

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.

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.

While Stefan and Valerie search for a magical herb that can keep him hidden from Rayna, Damon comes up with his own plan to take her down for good. However, while at The Armory, Bonnie makes a shocking discovery about Rayna that brings Damon’s plan to a screeching halt. Elsewhere, a conversation with Caroline leaves Stefan questioning their future together, while Matt decides it may be time to truly take a stand against the vampires of Mystic Falls. Finally, as the season’s middle chapter draws to a close, Damon’s desire to take himself out of the game ramps up as he races to complete unfinished business with Stefan and Bonnie.

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.

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.

In the aftermath of his brother's fateful decision, Stefan awakens to find himself thrown into a life or death situation with only his basic instincts to rely on. With time working against him, he sets off on a journey of survival while forced to confront a lifetime of irreversible damage Damon has done to their relationship. Meanwhile, desperate to save his brother, Damon follows an unusual lead he has come across, while Matt sends Valerie to Dallas to enlist Alaric's help in the search for Stefan. Finally, when Rayna discovers the emergence of a new threat, she sets off on her own mission to find Stefan before the others do.

Despite their best efforts to help Bonnie through the harrowing predicament she now faces, Damon, Enzo and Caroline realize their options are running out and drastic measures need to be taken. With their only chance of saving their friend lying inside the Armory, Stefan breaks the news to Caroline that they may need help from an unlikely source – her and Alaric’s twin daughters. Elsewhere, Enzo keeps Bonnie preoccupied by bringing her back to their cabin but when his plan takes an unexpected turn, it’ll be up to Damon to make the ultimate sacrifice to save his closest friends.

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.

When his experience in the Phoenix stone leads him to do the unthinkable, Damon finds himself without a care in the world, spiraling out of control and under the influence of a dangerous and reckless Julian. Refusing to give up on his brother, Stefan attempts to reason with Damon only to uncover the devastating reason for his descent. Elsewhere, Caroline begins having some dangerous side effects as a result of her supernatural pregnancy and is forced to turn to Valerie for help. Meanwhile, Bonnie, Nora and Mary Louise attempt to track down a ruthless vampire hunter named Rayna after they suspect that she has reemerged.

When Damon's risky attempt to save Bonnie takes an unexpected turn, the consequences of his actions forces everyone to band together to help her pull through. Meanwhile, when a new threat leaves Caroline's life in jeopardy, Stefan makes a rash decision that ultimately forces them to face the fallout from their relationship. Elsewhere, Enzo tries to hold it together as he painfully watch Bonnie in the fight of her life, while Matt takes matters into his own hands to save one of his closest friends.

In an attempt to make things right with his brother, Damon offers to have Stefan’s scar magically transferred to him, only to discover that doing so may come with some unexpected consequences. With time running out and Rayna closing in on Stefan, Valerie desperately attempts to reason with Damon before it’s too late. Elsewhere, after being framed for breaking Rayna out of The Armory, Enzo attempts to clear his name, but not before a violent run-in with Nora forces him to make an upsetting discovery.

Determined to capture an escaped vampire named Ambrose, who may be the key to getting Stefan back safely, Damon heads to Memphis with Alaric in tow. However, reluctant to step back into his former vampire hunting ways, Alaric makes his unwillingness to participate clear, while revealing the truth about the past three Damon-less years of his life. Meanwhile, in the psych ward, Bonnie meets a young woman named Virginia, who provides her with some valuable information about why The Armory may be after her. Finally, Enzo takes matters into his own hands when he learns some devastating news from Rayna.

With the traumatic effects of the Phoenix stone taking a toll on his brother, Stefan attempts to help Damon regain his grip on reality, while secretly struggling with his own experience in the stone. Elsewhere, Matt and Bonnie deal with the fallout after Julian and his men take over Mystic Falls, leading Matt to spiral out of control and into trouble with an officer named Penny. Meanwhile, Tyler returns to town for Alaric's baby shower and Caroline makes an upsetting discovery involving Alaric and his future plan for the babies.

With Bonnie's life at stake and an uphill battle ahead of them, Damon and Enzo lead the charge to save Bonnie before her condition worsens. Stefan reluctantly teams up with Matt for the sake of Bonnie and uncovers the truth behind Matt's anger towards him. Elsewhere, determined to help her best friend, Caroline joins Alaric on a mission and quickly realizes how much she's missed her former supernatural lifestyle. Finally, after their plan takes an unexpected turn, Damon makes a fateful decision that will forever change his relationship with Bonnie.

When Enzo’s efforts to protect Bonnie end up putting her life in jeopardy, they learn that Rayna may hold the key to her survival. With time running out and Rayna at the reins, Enzo and Bonnie reluctantly team up with Damon, who is desperate to save Bonnie’s life and to repair their broken friendship. Elsewhere, when Stefan travels to Dallas and comes face to face with Alaric, tensions escalate and they are forced to confront the fallout from Stefan’s absence in Caroline’s life. Finally, Enzo learns The Armory’s true motives behind their search for Bonnie.