Wonder Woman and Aquaman are under attack by five of the Legion of Doom (Scarecrow, Riddler, Cheetah, Black Manata, Bizarro) in Black Manta's Manta-ship. Batman, Apache Chief, and Superman come to their aid, but they all disappear as the rest of the Justice League and Legion arrive. The missing members are teleported to a planet by a being called Vartu who places them in contests to end their battle once and for all. Batman and Riddler vie in a maze, with Batman winning. Black Manta and Aquaman must cross the Lake of Terror and Manta wins when Aquaman has to rescue him. Cheetah and Wonder Woman must climb and cap a volcano and Wonder Woman wins. Apache Chief and Scarecrow must best a two-headed serpent and Scarecrow wins by stopping Apache Chief's efforts and lassoing the creature himself. Superman and Bizarro must stop a giant space robot with kryptonite beams and Superman wins. Vartu dumps the five Legion members into a pool of acid but the SuperFriends rescue them. While the missing members struggle against each other, the remaining Legion and SuperFriends call a temporary truce to track down their missing comrades together but the Legion backstab their allies at every opportunity in a substatomic world and a universe of geometric shapes. The Legion eventually find both missing groups and rescue everyone when Vartu turns against them. But the other SuperFriends find them when the Legion then turns against the League, and Vartu sends them all back to their own universe.