Batman prompts the League to investigate the new crime fighter, the Creeper. Things get rocky when the League must battle him-along with aliens and crooks-at a nuclear power plant.
The story begins as we are introduced to a character who calls himself The Mind Grabber Kid. He has accidentally discovered he can control matter with his mind and that he is about to use his powers for good for the very first time. Mind Grabber Kid uses his abilities to thwart a jewel robbery, but as he hopes to milk the applause of passers-by, he finds their attention on the local television shop. As Mind Grabber Kid walks away, full of resentment and feeling unappreciated, an alien spaceship approaches Earth and prepares to make contact with one of her citizens, Mind Grabber Kid. Seething about being outshone and seeing an opportunity for revenge, Mind Grabber Kid tells the aliens that the JLA are threatening to enslave the whole earth.
At their regularly scheduled meeting, the JLA have little to discuss until Batman suggests the team investigate the Creeper. Batman has already decided that he is one of the good guys and so rules himself out of the case as he does not want to prejudice the views of the other Leaguers.
The Creeper swings into action, but finds himself heavily outnumbered. Despite the fear he tries to instill into his opponents with his trademark maniacal laugh, he is slugged from behind - but not before the Atom joins the fray. Unknown to the Atom and the rest of the League, they are now being tailed by the aliens, and when they observe Atom slugging one of the criminals, they believe what the Mind Grabber Kid has told them. Donning something called Meta-caps (which allow them to duplicate the power of any opponent), the aliens head earthward to confront the JLA. The Atom slugs it out with his counterpart, but seems to think he will be unable to follow him into the sub - atomic universe ??? and is duped from behind in a move he himself has used countless times before!
The Flash is quickly overcome by an opponent who shows him a clean pair of heels and then simply trips him up, while Green Lantern is getting the better of his counterpart until of course the Meta cap allows its wearer to realise that GL's ring does not work on anything yellow. As Superman approaches, the Meta Cap recognises so many powers that it implodes due to not being able to cope. However, the aliens realise that Superman is powerless beneath a red sun and set off a chain reaction with their Magno units and Essence Converters to turn the sun red. Superman loses his powers and is defeated along with the other Leaguers.
At that moment Mind Grabber Kid enters the scene and convinces the aliens that the recovered Creeper is also one of the bad guys. A slug fest ensues between the Creeper and the aliens, but suddenly, the criminals Creeper was after in the first place emerge. Seeing the chance to off the JLA, the first gunman takes aim at Superman. However, Mind Grabber Kid uses his telekinetic powers to revive Superman and the Man of Steel soon rounds up the hoods with the help of the Creeper. Supes tells the Creeper to make himself scarce, Mind Grabber Kid admits he lied about the League and the aliens depart.