Countdown is a comic book limited series published by DC Comics, which debuted on May 9, 2007, directly following the conclusion of the last issue of 52. The series is written primarily by Paul Dini, who will act as a showrunner, with a rotating team of writers and artists. Countdown consists of 52 issues published weekly for one year, crossing over with noteworthy and significant titles published by DC. The series covers much of the fictional DC Universe and is told in parallel narratives, through the interconnecting stories of a cast of characters, and frequently crosses over with various other DC titles. Within Countdown every four issues will directly correspond to a month, allowing such creative liberties as flashbacks and cliffhangers.
The series follows the success of the previous year's 52-issue weekly "real-time" series, 52, which in contrast did not cross over with DC's other regular titles. 52 concluded with the revelation that the Multiverse (a storytelling device which posits the existence of alternate realities) exists, and the Multiverse now serves as a backdrop to several stories in Countdown. As of issue #26, the series will be renamed Countdown to Final Crisis, in the vein of the previous Countdown to Infinite Crisis limited series, albeit larger. The stories taking place in Countdown are expected to set the stage for the approaching "Final Crisis" series which like its predecessors, Infinite Crisis and Crisis on Infinite Earths is intended to be a major story in the history of the publisher which may possibly restructure the DC Universe in which its stories are set.
A backup story entitled "History of the Multiverse" appears in issues #49 through #39, with the creative team of Dan Jurgens and Norm Rapmund. It relays the publication history of DC Comics from an in-universe perspective to the reader, detailing the first meeting of the first and second Flash in "Flash of Two Worlds" through to the preceding events of 52 and One Year Later, as told by the fictional Monitors, who appear within the main story. Beginning with Countdown #38, the backup stories will tell the origin stories of various supervillains in "Secret Origins of the Super Villains", similar to those of various superheroes told in 52.