 The Rock Men and Chrystal Men, alien races of the planet Mercury, are at war and use Earth as a launching base for their conflict. The Rock Men send a force that drills into Earth s surface to establish a beam transmitter that can detonate the mammoth energy orb that powers the Chrystal Men nation, an act that will destroy the planet and wreck the entire solar system. While a Chrystal Man force flies to Earth to stop their enemy, the Rock Men fight back with energy weapons that attract a cosmic storm of debris, bringing out Superman, Green Lantern, and Hawkman to intercept the space bombardment, while on the planet surface two more Justice Leaguers, The Flash and The Atom, track down the Chrystal Men s ship. When the JLA learn the full extent of the Rock Men s plan, they go into action to stop them and also to bring an end to the two sides  conflict before it s too late.