Issue #1, “The Summoning”
The year is 1985, and the universe containing Earth-3 is slowly being obliterated by a wave of anti-matter. Lex Luthor, a hero on this world, tries to save his only child by sending him to Earth-1; more specifically, the satellite headquarters of his allies, the JLA (unfortunately, Luthor is unaware that the satellite is abandoned, and so no one is there to rescue the child from the craft).
The mysterious Pariah appears just as Earth-3 vanishes, and cries out in despair knowing he can do nothing to save them. Meanwhile, the mysterious being known as the Monitor decides the time to act is now, and so he bestows part of his power on his young assistant, the woman known as Harbinger. She splits into multiple copies of herself and flies off to retrieve a select group of heroes and villains. However, one of her incarnations is zapped by a shadowy figure, apparently placing her under its power.
After she brings the group to the Monitor’s satellite, they are all attacked by “shadow demons.” The Monitor dispels the shadows and informs the assembled heroes and villains that their worlds are about to die.
Issue #2, “Time and Time Again”
Strange things are happening at places throughout the timestream, from Anthro’s prehistoric village to the 30th century (the home era of the Legion of Super-Heroes). In our time, both Batman and the Joker see a vision of the Flash crumbling before their eyes. On his ship, the Monitor tells the assembled group that the multiverse is threatened by the Anti-Monitor, his opposite number from the anti-matter universe.
He then dispatches the heroes and villains to various points in history on both Earth-1 and Earth-2 to set up cosmic “tuning forks” that will keep the Anti-Monitor at bay. While the tainted Harbinger continues to plot, young Alex Luthor, who is rescued from his ship by the Monitor, is aging rapidly. Psycho-Pirate — one of the super-beings summoned by the Monitor — attacks Pariah but is teleported away by the unseen foe, who orders him to obey.
Issue #3, “Oblivion Upon Us”
Earth-1’s Flash sees the anti-matter wave approaching the future Earth where he lives, and he travels back to the 20th century to warn other heroes. He barely has time to say “we’re screwed” before he vanishes.
The anti-matter wave starts sweeping across Earth-1, and shadow demons attack the tuning forks. Our heroes fight and die defending the machines from the demons. While Earth is slowly being destroyed, the Monitor isn’t sure if his plan will work in time.
The heroes of the DCU are only beginning to realize the scope of the danger they are in, and it may already be too late. The Flash inexplicably disappears; the Teen Titans try desperately to curb the death and destruction caused by this cataclysmic event, and the Legion of Super-Heroes stand helpless as a wave of anti-matter threatens to wipe them and their world from existence forever.