Pariah enlists Black Lightning to help stop the Anti-Monitor after Flash-90 shares what he learned from his battle in ‘Elseworlds.’ With the help of Black Lightning, Barry, Cisco and Killer Frost come up with a plan that could save them all. Meanwhile, Iris has a heart-to-heart with Ryan Choi, while Oliver and Diggle return to an old familiar stomping ground.

The crossover starts on Supergirl S05E09 and Batwoman S01E09. It continues on Arrow S08E08 and Legends of Tomorrow S05E01.

Barry meets Black Lightning at the Hall of Justice after things take a dire turn with Despero. Iris suspects something is off with Despero's vision of the future so she seeks help from a powerful ally.

Barry is shocked when Eobard Thawne returns in the most unexpected way, and with a tie to a loved one. Damien Darhk offers advice to Barry but there is a catch. An epic battle begins with Reverse Flash pitted against The Flash, Team Flash, Batwoman, Sentinel and Ryan Choi.