The Monitor sends Harbinger to gather the worlds' greatest heroes - Supergirl, The Flash, Green Arrow, Batwoman, White Canary, The Atom and Superman - in preparation for the impending Crisis. With their worlds in imminent danger, the superheroes suit up for battle while J'onn and Alex recruit Lena to help them find a way to save the people of Earth-38.

The group uses Ray's invention to track new recruits to help save the universe. The Monitor sends Iris, Clark and Lois in search of a mysterious Kryptonian, while Kate and Kara head out to find Bruce Wayne. In addition, Mia challenges Sara, Rory discovers a hidden talent, and Lex Luthor returns.

Pariah enlists Black Lightning to help stop the Anti-Monitor. Oliver and Diggle return to a familiar place.

Stuck in the Vanishing Point, the Paragons search for a way to escape; Oliver reveals that he has become something else; the origin stories for The Monitor and Anti-Monitor are revealed.

Worlds lived, worlds died. Nothing will ever be the same.