Flash and Green Lantern go after an alien ship that has been spotted over the city.
Police forensics scientist, Barry Allen, and test pilot, Hal Jordan, are hanging out, together, in Coast City. The two men eventually make it back to the estate of Jordan's boss, Carol Ferris. Having tied each other in a sporting contest, the two men compete in an archery competition, to determine the winner. Suddenly, an unidentified flying object buzzes the grounds of the Ferris Estate. In the confusion, Allen and Jordan slip away, only to reappear in their costumed identities, the Flash and the Green Lantern. The two heroes are in pursuit of the strange craft when it captures the Flash in a tractor beam. Green Lantern pursues the craft to a distant alien world.
Though the craft releases the Flash, Green Lantern continues his pursuit. Green Lantern grounds the craft with the power of his ring, only to discover it is unmanned. Suspecting he may have been lured into a trap, Green Lantern sets off to rendezvous with the Flash. The Scarlet Speedster finds himself slowly trudging through a snowstorm, one that seemingly formed out of nothingness. A massive creature coalesces out of the snow before him. Vibrating at super-speed, the Flash dissipates the creature before it can attack. All at once, the snow storm ends.
The Flash is confronted by a transparent alien, armed with a strange gun. The alien fires on the Flash causing the Flash to be upended. No matter how hard he tries, the Flash can't right himself. Learning to run on his hands at super-speed, the Flash kicks his attacker into unconsciousness. Meanwhile, Green Lantern is drawn down to the planet's surface by a rapid increase in the planet's gravity. Breaking his fall with a power ring constructed mattress, Green Lantern finds himself held fast by the planetary gravity. A river of molten metal erupts out of a nearby hill. Mustering the full force of his willpower, Green Lantern manages to raise just high enough to avoid being consumed.
All at once, gravity returns to normal. The Green Lantern meets back up with the Flash. While comparing notes, the two men are suddenly grabbed by a living mountain range. The Flash vibrates his way to freedom. The Green Lantern constructs a ring powered pile driver to break himself free. With the entire planet seemingly trying to kill them, the two heroes depart, and return to Earth. Upon arriving in Coast City, the two heroes are stunned to see an enormous robot looming on the outskirts of town. Racing to confront it, the pair of heroes are stopped short by a holographic alien head, barring their path. The alien, a Myrmiton, telepathically informs the two heroes that Earth has been conquered.
The Flash and the Green Lantern were lured away, off world, to give the Myrmitons the time they needed to take the Earth. Holding the entire Earth hostage, under the threat of destruction by cosmic radiation, the Myrmitons force the Flash and the Green Lantern to surrender. The Green Lantern allows the Myrmitons to draw away his power ring. The Flash allows the Myrmitons to bathe him in cosmic radiation, neutralizing his super-speed powers. No longer in possession of their great powers, the Flash and the Green Lantern dejectedly wander the streets of Coast City. Speaking to the Green Lantern telepathically, the Flash reveals that all is not how it seems.
Moving so fast that he left an after image of himself behind, the Flash raced into a department store and grabbed the fake power ring off a Green Lantern mannequin, while also carrying the Flash mannequin back with him. Moving faster than the eye could see, The Flash removed the real power ring from the Green Lantern's finger, replacing it with the replica. The Flash then placed the Flash mannequin in his place, so that it was bombarded with the power destroying cosmic radiation. The Myrmitons discover the Flash's ruse, just as the two heroes are racing up towards their base. The Myrmitons' headquarters, however, is protected by a powerful force field.
Stopped by the field, the Flash and the Green Lantern are easy targets for the Myrmitons, who disintegrate the two heroes with cosmic rays. Once again, though, the two heroes have perpetrated a ruse. Aware of the Myrmitons' force field, the Green Lantern animated the two mannequins, sending them on a frontal assault. The real Green Lantern used his power ring to tunnel under the base's defenses. Taking the Myrmitons by surprise, the Flash and the Green Lantern are quick to defeat the alien conquerors. The Flash and the Green Lantern take a few of the Myrmitons prisoner, holding them hostage indefinitely, as insurance against future attacks. Before they can be swarmed by reporters, the Flash and the Green Lantern return to the Ferris Estate, as Allen and Jordan. Resuming their archery contest, both men throw the game, to end their competition in a tie.