In 1919, Rebekah worked in a sanatorium. She finds herself back there and locked up as a witch who is seeking revenge plans to reveal her darkest secrets. Elijah makes a decision that puts the others in further danger.

Hayley atempts to save her unborn baby from the witches. Francesca meets with Oliver and Jackson to decide the future of the werewolves in New Orleans.

Cami teams up with Marcel and Gia after she becomes suspicious of her faculty advisor Vincent. Lastly, in a surprising turn of events, Klaus comes face-to-face with a visitor from his past.

Rebekah becomes interested in a girl. Hayley struggles with coming clean and is surprised by something Jackson admits. Klaus learns something and heads to confront Hayley. Vincent sets his eyes on Marcel for answers to what Klaus is hiding.

Following a tense run in, Elijah believes that Klaus is up to something. Kaleb needs Rebekah's help.

With time running out, Klaus' ultimate plan to protect baby Hope at all costs continues to take shape.Source: CW

In order to uncover what his old acquaintance Tristan is really up to in New Orleans, Elijah considers attending a gala thrown by a mysterious group of ancient vampires known as The Strix, while Hayley invites herself to attend with him. There, Marcel is approached with an enticing offer made by a mysterious woman named Aya, but he quickly realizes that things are not always what they seem. Elsewhere, when a vital component of Lucien's plan goes missing, he and Klaus form a tentative alliance in order to find it.

When a dangerous affliction threatens to expose one of her siblings, Freya searches for a way to reverse the crippling curse even as she finds herself the target of The Strix's latest plan. Elsewhere, Klaus keeps a watchful eye over Cami while she attempts to help Detective Kinney, whose life has begun to spiral out of control as a result of Lucien's compulsion. Meanwhile, a confrontation with Marcel causes Vincent to reevaluate his decision to stay out of witch business, and Hayley's attempt at a quiet Christmas with Jackson and Hope results in an unexpected surprise.

With the threat of the prophecy looming over their heads, Klaus and Elijah find themselves rendered useless inside a magical trap, while Aya and The Strix's coven of witches move forward with a risky spell that could take one of them down for good. Elsewhere, Freya leads the charge to get her brothers back and enlists the help of Marcel, Hayley and Stefan Salvatore, an old friend of Klaus', whose unexpected arrival may be the key to their survival. Finally, Davina moves forward with a dangerous plan that brings her one step closer to reuniting with Kol.

The crossover starts on The Vampire Diaries S7E14 Moonlight on the Bayou (I).

After months of thwarting off dangerous threats and deadly attacks, the Mikaelson siblings finally come face to face with the one person that could lead to their ultimate demise. With the stakes higher than ever and the compound overrun by an army of his oldest sworn enemies, Klaus is put on trial for centuries of atrocities he’s committed. Meanwhile, Marcel, who has been spiraling out of control following an act of betrayal by those closest to him, is stunned by the unexpected arrival of someone from his past. Finally, Elijah, Freya and Kol frantically search for a way to save their family before it’s too late.