Finally the SUPERMAN tie-in adventures to the massive ZERO HOUR crossover are collected here! Time is collapsing in on itself. The villainous Extant has ushered in a series of black holes that are swallowing the universe--past, present and future! Superman, like everyone else in the DC Universe, has seen time loops affect his life. The result? The past is not what it should be. Krypton never exploded. The Kents never found a baby in a Smallville field. Superman isn't the protector of Metropolis. How can the Man of Steel put back time as it should be? Legendary comics writers Dan Jurgens, Karl Kesel, Louise Simonson and more present the tales tying into the classic ZERO HOUR event, now collected here for the first time! Collects ACTION COMICS #0 and #703, ADVENTURES OF SUPERMAN #0 and #516, SUPERMAN #0 and #93, STEEL #0 and #8, SUPERMAN- MAN OF STEEL #0 and #37 and SUPERBOY #0 and #8.