Justice League of America, Vol. 1

In a gambit set in motion during his initial encounter with the Justice League (in issue #41), the Key gives the super-heroes an irresistible command not to leave their headquarters for one hour, and at the end of that time to kill each other. They find themselves unable to leave the Secret Sanctuary, until Superman finds a way out, by time-traveling three years into the past, thus catapulting his past self into the future to take his place. The Superman of-three-years-past is unaffected by the Key's command, and so is able to extricate his fellow members from their predicament by overpowering them all and forcing them out of the meeting room. The entire team then battles the Key and his men, but as the one-hour deadline draws near, Superman is again forced to battle and defeat the other members, knocking them unconscious before they can carry out the Key's deadly orders and kill each other. He then forces the Key to countermand his deadly order. Later, the members determine which of them was to have killed which: Snapper Carr was to have been Super-man's executioner, using concealed Kryptonite, while the returned Superman-of-the-present reveals that his victim was to have been Batman. In the near past, he avoided the kill-command by having Green Lantern and Wonder Woman join forces to subdue him until the danger had passed. This entire adventure is seen through the eyes of time-traveling tourists from the future.