Zero Hour: Crisis in Time was a miniseries that spearheaded DC''s big 1994 crossover event Zero Hour. Zero Hour was designed to remedy continuity errors that had crept into DC titled since the Crisis on Infinite Earths, and relaunch all of the heroes from the same point in time. The Zero Hour event took place in a five-issue miniseries (numbered in descending order from 4 to 0), and with 27 crossover books, ranging from Action Comics to Wonder Woman. Showcase ''94 #8-9 served as a backstory to the event, highlighting the major villain Extant''s creation. Then Zero Hour : Crisis in Time #4-0 highlights the major story arc, including Hal Jordan''s first appearance since the Emerald Twilight story arc in Green Lantern. Issues were released in descending order, providing a countdown to the restart of the DC Universe.