Reports were coming in from all over the world about odd events filling people with a strange sense of deja vu. Multiple, slightly different versions of specific people and moments were cropping up all over the place. It was first brought to Superman's attention by the Batman...and then by another Batman...and then by yet another Batman...until the Man of Steel found himself dealing with no less than four distinct versions of the Dark Knight--each different, yet exactly the same.

With Professor Hamilton's help, Superman and Batman were able to figure out that the strange reality-clashing was due to a temporal disturbance caused by an outside force. This force revealed itself to be a being called Extant, seemingly determined to rewrite reality as it saw fit. Superman led a charge of most of Earth's heroes against Extant, who in his defeat was revealed to be merely the pawn of another, far more powerful and dangerous villain... Green Lantern!

Hal Jordan, the greatest Green Lantern in the history of the Corps, had become unstable following the destruction of his home, Coast City, by the Cyborg and the alien tyrant Mongul. In a rage, he had gone to Oa, the home world of the Guardians of the Universe, and absorbed the central power battery into himself, giving himself unlimited power. Now calling himself Parallax, he used that power in a mad scheme to rewrite the history of the universe, intending not only to save Coast City but to undo or prevent all the events he felt should not have happened--including events like the destruction of Krypton!

His mad scheme was stopped by Superman and the other heroes, but not before some of his changes had taken effect. It would take some time for the full implications of Parallax's actions to manifest themselves in the universe. In the meantime, however, Superman had to face a new threat, from an unlikely source.