Doomsday: Prologue. "Time Ryders!" Waverider and the Linear Men have always been at odds about how to monitor the time stream. But the unexpected happens when the Linear Men actually ask the golden time-traveler to join their team. But can Superman stand idly by while the Linear Men possess this much power over time? Does he have a choice? Plus, on the last page, powerful pounding fists are the harbinger of quite possibly the most dangerous threat the Earth has ever faced, and the issue ends with the ominous warning "...Doomsday is coming!"