When Lex Luthor and his Legion of Doom try to use cryogenic rays from orbital satellites to expand the Earth's polar ice caps, causing a massive drop in sea levels and creating new islands they intend to rule, Superman and the Justice League thwart the evil plan. Through a mishap, Luthor is entombed in a sheet of ice and presumed dead. Centuries later, in the utopian 31st century, teenage superheroes-in-training, Dawnstar and Karate Kid, visit the museum where Luthor has been in suspended animation for nearly a millennium and accidentally release him. Luthor discovers Superman's true identity and also steals an ancient device called the Eternity Glass, which allows the user to manipulate the fabric of time and space. Along with the Legion of Doom, Luthor travels back in time to eliminate Superman, Wonder Woman and Batman before they become superheroes.