The JLA is brought to a subatomic world in order to save its people.
The members of the JLA find themselves shrinking into a world so small that the Atom looks like a giant. Seeing what has happened to his colleagues, the tiny titan follows his team mates to be confronted by the three gladiators of the micro world. These three explain that they are the protectors of their world's earth, sea and sky - but using their powers via their radiation helmets was shortening the life span of the very planet they were sworn to protect.
The three guardians had called the JLA to their world in order to help them remove their so called "indestructable" helmets and therefore save the planet. Despite their best efforts, the JLA can't beat the guardians and Superman, Wonder Woman and Green Lantern find themselves trapped in an "escape proof" cage.
Try as they might, each member of the League in turn cannot move the bars of that cage one inch. As Superman pointed out to the Martian Manhunter, "If I can't bend these bars, neither can you." Suddenly Batman steps forward and demands everyone remains quiet. Then, to the astonishment of everyone else, he proceeds to bend the bars of the cage. Batman has realised that once a person hears something on this world, they believe it / it comes true. Therefore, since each JLAer in turn had heard that they would not be able to bend the bars, none of them had been able to do it.
Realising that they had all heard that the three guardians wore "indestructable" helmets, the Atom returns to earth, where he brings Snapper Carr back to the micro world. Covering Snapper's ears at all times so he cannot be told what is or isn't possible on this world, the JLA use their mascot in order to defeat the three guardians of the micro world.