The Justice League of America assemble for a meeting. Aquaman, the Flash, J'onn J'onzz, the Manhunter From Mars, Superman and Wonder Woman are abducted. The five heroes find themselves on the alien world, Marithania. In the city of Exactikon, the five heroes are brought before the Impossibles. Feeling that none of the heroes have truly earned the right to have super-powers, the Impossibles have deemed it time to remove them. First, the Impossibles steal away Aquaman's telepathic powers. Then, the Flash's super-human speed. As Marithania orbits a red sun, Superman is already powerless. The Martian Manhunter loses all of his myriad powers. Finally, Wonder Woman is reduced to normalcy. Almost immediately, the Impossibles are attacked by their age-old enemies, the Contras.
Despite the loss of their super-human abilities, the Justice League of America still engage the Contras. Aquaman attacks a giant, mobile brian. The brain counters with a telepathic assault, one that would have slain Aquaman, had he still possessed his own telepathic powers. J'onn J'onzz, the Manhunter From Mars, is engulfed in flames. Fortunately, with the loss of his powers, so, too, has the Martian Manhunter lost his extreme vulnerability to fire. The Flash survives a vibratory attack that would have slain him, had he still possessed his super-human speed. The Justice League of America is soundly defeated in their first encounter with the Contras. The Justice League of America switches tactics, focusing the sun's rays through a large lens, to use as a weapon, against the Contras.
The lens, however, is destroyed before the Justice League of America can fully employ it. Switching tactics again, the Justice League of America decide to turn their former weaknesses into strengths. Superman wields a large chunk of Kryptonite against the Contras, felling a large crystal warrior. The team splits up, to lure the individual Contra warriors away from the Impossibles. J'onn J'onzz, the Manhunter From Mars leads the flora warrior back to it's ship. The Martian Manhunter lights a torch, but drops it when he is felled by the flora warriors's attack. Grabbing a handful of dirt from soil sample bins, J'onn J'onzz, the Manhunter From Mars, repels the flora warrior back. The flora warrior steps on the torch, and is consumed in flames. Aquaman and Superman lead the mobile brain, and the neon warrior, to the sea.
Using a rope fashioned from seaweed and starfish, Aquaman drags the brain into the sea, then holds it underwater until it drowns. Superman is engulfed in Kryptonite dust, by the neon warrior. Superman dodges the neon warrior's next attack. Astonishingly, the neon warrior's weapon's fire continues traveling past Superman, until it hits Marithania's red sun, turning it yellow. Superman hurls his kryptonite rock at the neon warrior, defeating it. Wonder Woman and the Flash use teamwork to survive the Contra's attacks. The Flash stumbles in front of the spiral warrior, and is bathed in hazardous chemicals, just as the crystal warrior fires an energy beam through them, to hit Wonder Woman. The Flash uses the powerful vacuum of his costume ring, to compress the spiral creature down into the ring.
The crystal warrior's energy blast projects Wonder Woman back in time. Wonder Woman tampers with the Impossible's power stealing device, so that she never loses her super-powers. Wonder Woman destroys the device, then returns to the present. Wonder Woman shatters the crystal warrior. Wonder Woman is surprised to see the Flash dodge the falling crystal shards, using his super-human speed. The chemical bath he received, coupled with the crystal warrior's energy blast, has restored the Flash's powers. Under Marithania's new yellow sun, Superman, too, has regained his powers. Coming in contact with Martian soil has, inexplicably, restored the Martian Manhunter's powers. The brain's telepathic assault on Aquaman, as it was being forcibly drowned, has restored Aquaman's telepathic powers.
The Impossibles justify their actions, by pointing out that the Justice League of America would have been killed outright, in the first attack, had they still possessed their super-powers. The Impossibles return the heroes to the Secret Sanctuary.