On the run, Speeda Demon realizes that the only way to keep Hero Factory from getting him is to get them first. From every corner of the galaxy, he assembles an army of criminals. Their mission: wipe Hero Factory right off the map. Outnumbered and outpowered, the heroes Furno, Nex, Stringer, Bulk, Breez, and Stormer XL must come up with a way to win--or else see the galaxy become an empire of crime.

The heroes receive dire news: prior to their original capture, Core Hunter, Voltix, XT4, and Thornaxx stole four components of what is said to be a devastating super-weapon called "The Doom Box." This device grows larger on activation, encompassing anything in its path, then collapses in on itself--a serious danger enough--but the box is capable of growing to the size of an entire galaxy! Now that the villains have escaped, they are believed to be...

Stormer sends Bulk and Furno to investigate why their planet can no longer communicate by radio and to find out what happened to Stringer, who sent a warning message from Tranquis VII and then vanished.