In the year 11,960 A.D. the super-criminal known as Xotar is fleeing the interstellar police. Having found the tattered remains of Wonder Woman’s diary which documented the adventures of the Justice League, Xotar knows that he is destined to travel into the past and battle them where he believes that at least one of his super-weapons from the future will defeat the Justice League.
Travelling to the past, Xotar targets the Leagues honorary member, Snapper Carr. Using him as a pawn at the next Justice League meeting, Xotar immobilises the group and has them challenge him to see if they are able to defeat him. The arriving members are Aquaman, Green Lantern, Flash, Batman, Martian Manhunter and Wonder Woman. He first challenges the Flash, who is able to destroy Xotar’s shrink ray. Next he challenges Aquaman and Martain Manhunter to destroy his de-evolution ray, which the duo manage to destroy. Next Xotar challenges Batman, Wonder Woman and Green Lantern to try and stop his magneto-bubble device, which they succeed in destroying. Believing that his final weapon, an illusion caster will destroy the Justice League, he allows them all to attack at once.
Having the upper hand at first, the timely arrival of Superman turns the tide, the Man of Steel destroys Xotar’s weapons and the heroes return Xotar to his own time and turn him over to the authorities. As history would have it, the words in Wonder Woman’s diary which were rubbed out over the centuries indicated that none of Xotar’s weapons would defeat the League.