Synopsis

The wedding of Barry and Iris unites the heroes, but the celebration is disrupted by villains from Earth-X. United, the superheroes rally with the aid of allies such as Citizen Cold, The Ray, Felicity Smoak, Iris West, and Alex Danvers, facing their most dangerous adversaries yet. Green Arrow, Supergirl, The Flash, and White Canary lead Earth's greatest heroes into battle to safeguard the world. The crossover event begins with *Supergirl* Season 3, Episode 8, "Crisis on Earth X" (Part I) and