When the Legends discover a new Encore, Sara, Rory and Ava end up crashing a high school reunion to attempt to stop a serial killer from finishing unfinished business. The Legends devise a plan to send Nate, Ray, Nora, Behrad and their hostage Zari, back in time to try and intervene in order to try to save everyone including them. Meanwhile, Constantine is annoyed that Charlie has been squatting in his old home, but it might be the blessing in disguise they were not looking for.

With Sara still away from the Waverider, the Legends find a new Encore with Ava's new invention, the Prognosticator, and must now try to defeat Genghis Khan in 1990s Hong Kong. Constantine's life is hanging in the balance, and Ray, Nora and Gary all try to help him, but Constantine tries to make a deal with Astra instead. Meanwhile, Behrad has been confused about Charlie's recent behavior, but they all learn why Charlie is trying to out run her past and from what.