"CRISIS FROM YESTERDAY!"
The Lord of Time launches a scheme to control the flow of time through his living computer, the Eternity Brain, but to correct a fatal flaw in his scheme, he is forced to draw five heroes out of the past, give them super-powers, and pit them against the Justice League and Justice Society.
The Viking Prince, Jonah Hex, Miss Liberty, Enemy Ace, and the Black Pirate cause an explosion at the joint meeting of the two teams which sidelines all but eight members of the groups. In a follow-up battle, the Viking Prince and Black Pirate defeat Flash, Huntress, Doctor Mid-Nite, Elongated Man, and the Earth-2 Wonder Woman, while Superman, Hawkman, and the Star-Spangled Kid fall before the forces of an airborne Enemy Ace, Jonah Hex, and Miss Liberty.
Recovering, the heroes set out to avenge this defeat, which is precisely the Time Lord's intention: his irrevocably programmed computer will stop the flow of time forever unless the JLA and JSA can prevent it.