With Washington, D.C. in the hands of The Omega Man and the full extent of his horrific power revealed, the JLA is forced to make a difficult decision. Is there no choice for the World's Greatest Heroes but to team with the World's Worst Villains the Crime Syndicate in order to save both Earths? How will this desperate action be affected by Ultra Man's betrayal of everyone. . . and the reappearance of Dark Supergirl?