“THE BATTLE AT THE EDGE OF FOREVER!” Albon and Nordon, two survivors of a mostly dead alien race called the Krill, observe Supergirl and the Justice League's quest to find their missing champion, Superman. To satisfy their own curiosity, they bring the Justice League and one of its greatest enemies together for a final battle.
The Hawkman's starship closes on Despero. Unbeknownst to the two adversaries, their conflict is observed by the last living survivors of the ancient Krill race, Albon and Nordon. The aliens teleport the Justice League of America, Supergirl, and Despero, to their space station. The Elongated Man immediately attacks Despero. The Elongated Man suffers a savage assault, at Despero's hands, requiring rescue by Supergirl. Wonder Woman attacks Despero. The alien dictator is baffled by Wonder Woman's presence, believing her to already be a prisoner aboard his ship. Needing time to make sense of the situation, Despero teleports away.
Wonder Woman offers comfort to Supergirl, who is distraught over Superman's disappearance. The Krill play back recent events in the combatants minds. Supergirl had contacted the Justice League of America, to enlist their aid in searching for the missing Superman. The Man of Steel had been drawn to the planet, Sirkus, to aid the planet's inhabitants against Despero. Superman failed to defeat Despero, and was taken prisoner. The Krill find themselves oddly engaged by the violence between Superman and Despero. The Krill decide to encourage more violent activity between Despero and the Justice League of America.
The Krill teleport the Batman, and the Hawkman, to Despero's location. The Hawkman leaps to the attack, but Despero, who has wandered into an armory, counters with an alien weapon that solidifies air. Both the Hawkman, and the Batman, are defeated in a matter of seconds. Despero is about to slay his foes, when the Krill teleport Despero to another world. The Atom, and Wonder Woman, are teleported to the same world. After suffering several strikes from the Atom, and Wonder Woman, Despero uses his third eye to mentally enslave Wonder Woman. The Amazon Princess, under Despero's command, uses her Lasso of Truth to generate a sandstorm, felling the Atom.
Despero, along with Wonder Woman, teleports back to the Krill space station. Despero, though, finds that he materializes alone. Wonder Woman did not teleport with him. The Elongated Man, and Supergirl, attack Despero. As they tackle Despero, all three are hurled into another strange alien world, inhabited by trees of glass. Despero suffers a breakdown, brought about by the constantly shifting battlegrounds. The Krill take over Despero, forcing him to fight. Despero lunges at Supergirl, in a murderous fury, and begins strangling the Maid of Steel. The Elongated Man tries to pull Despero off of Supergirl, but is beaten into unconsciousness.
Supergirl beats Despero down again, and again, again, only to see him rise and continue to attack her. Finally, Supergirl calls out the Krill, demanding they reveal themselves. Learning that the Krill are excited by violence, Supergirl suggest sweetening the experience, by wagering on the outcome. Albon bets on Supergirl, while Nordon champions Despero. Supergirl throws Despero into orbit. Realizing that Nordon has provided Despero with a force field, Supergirl strikes Despero with all her full might, felling him. Angered at Albon's victory over him, Nordan attacks Albon. Supergirl leaves the two aliens to fight amongst themselves.
With Despero in custody, and Superman released from Despero's ship, the Justice League of America, and Supergirl, return home.