As the multiverse faces imminent destruction, the Justice League teams up with heroes from various Earths to confront the Anti-Monitor, whose relentless assault threatens all realities. Batman, Superman, and Wonder Woman spearhead the effort, coordinating a strategy to harness the combined might of their allies, including the enigmatic Harbinger and the technologically adept Mister Terrific. As reality shatters around them, each hero grapples with personal dilemmas and sacrifices, pushing their limits to safeguard the multiverse. On Earth-2, Barry Allen/The Flash and Kara Zor-El/Supergirl uncover crucial intelligence on the Anti-Monitor's vulnerabilities, galvanizing hope among their ranks.

Meanwhile, fractures within the team surface, compounded by burgeoning tensions between alternate versions of familiar heroes. With time running out, they embark on a desperate mission to retrieve a cosmic artifact capable of stabilizing the collapsing universes. Green Lantern and Martian Manhunter venture into uncharted territories to secure unconventional alliances, while Cyborg devises a plan to merge multiple Earths into one unified reality. The ensuing battle tests the valor and resilience of every hero involved, setting the stage for a cataclysmic showdown. Ultimately, they must confront not just an insidious enemy, but also the darker aspects of their destinies.