To save the woman he loves, the greatest hero of all time becomes the pawn of ultra-dimensional forces when a wounded emissary from a world of doomed super gods comes to Earth on the eve of the Final Crisis. His mission: recruit Superman's help against an epic, reality-spanning menace that originated in the Crisis on Infinite Earths!
The issue starts with Superman being blasted by what looks to be a Monitor, who is chipping away at Superman’s "cosmic armor". We follow Superman back in time to see Clark Kent sitting next to Lois Lane's hospital bed saying that he'll do anything to save her. The Monitor Zillo Valla shows up and stops time, saying that if Superman helps her, she will save Lois' life. Superman follows her to her ship, where it is being attacked by another ship. Superman realizes that Zillo Valla has recruited Supermen of other universes to help in her mission: Ultraman from the Anti-Matter Earth, Captain Marvel of Earth-5, Overman of Earth-10, and Captain Allen Adam, the "Quantum Superman" (and a Doctor Manhattan look-alike), of Earth-4. The enemy ship takes damage from Ultraman and crash lands on Earth-51, part of the "graveyard universe", named that after the fight between Superman-Prime and Monarch destroyed most of the universe. The Monitor's ship then lands in Limbo, where the Supermen are greeted by Merryman. Superman and Captain Marvel make their way to the Library of Limbo to see the one book that Merryman tells them is there.
When they get to the Library, they see that the book is a book with an infinite number of pages, all occupying the same space. Superman and Captain Marvel realize that if they can get the book to the ship, the ship will be able to process all of the infinite number of stories and would figure a way to fix itself. When they try to pick up the book, it starts to tell them a story about the Monitors.
The story says that there was one Monitor who was as large as the void itself, but a flaw was found in it. To contain this flaw, the Monitor creates the Multiverse to contain it, but it didn’t foresee the birth of complex life within the Multiverse. So the Monitor sends out a probe, possibly the original Monitor from Crisis on Infinite Earths, to investigate the abnormality within the flaw. It witnesses the events of the original Crisis and encounters the concept of "stories" and feels threatened by the existence of "stories", realizing that it has no defense against it. The Monitor seals the flaw, and all that seems to remain is a statue of Superman, dubbed "a vast, uncanny form". After eons of the form standing idle, the race of Monitors develops around it. They determine, after a few eons, that the form must be some sort of weapon that will help them against some ultimate enemy. Meanwhile, as blood falls from the sky, presumably from the Bleed, the Eater of Life, called Mandrakk, senses his freedom.
There is suddenly a burst of lightning as Superman and Marvel are blasted back from the book and Marvel is transformed back into Billy Baston, who can't remember who he is or his magic word. Superman makes his way back to the ship, telling Captain Adam that he’ll need his help to get the book. Demanding answers, Superman rips off Zillo Valla's door, only to see her sucking out the blood, vampire-style, of Overman. It turns out that she needs to drain "life" from Overman in order to power her ship. Valla tells Superman that the destroyer from earlier is considered Mandrakk's nanotechnology and the he has found them. Captain Adam tells Superman to come outside; the sky has just shattered. The sky has turned red, Ultraman is holding the infinite book and saying that evil wins, and a ship bearing, what looks like, Brainiac’s symbol appears in the sky.