The story picks up with the remaining Earths trapped in a "pocket universe" called the Bleed to escape an antimatter wave. The Threat: The Anti-Monitor seeks to destroy all of existence. Heroic Last Stand:

Justice League: Crisis on Infinite Earths - Part 2, also written by Andy Diggle and illustrated by Mike Perkins, continues the story from Part 1. The stakes are higher than ever as the Justice League faces off against the anti-monitor and his minions.

Part 1 sets the stage for the larger event, introducing readers to the concept of the multiverse and the anti-monitor's threat. The story features a diverse cast of characters, including Superman, Batman, Wonder Woman, and others, as they attempt to comprehend the nature of the threat and find a way to stop it.

To fully understand the stakes, it is recommended to watch the previous films in this specific continuity:

For a casual viewer who hasn’t watched Justice League: Warworld or Legion of Super-Heroes , the first twenty minutes of Part 1 will feel like reading a dictionary thrown into a blender. The film assumes you know who Supergirl of Earth-96 is. It assumes you remember the Pariah’s backstory. This is a film for completionists.