Superman, Batman, Wonder Woman, the Flash, Green Lantern and the Martian Manhunter - each a mighty hero in their own right. The Ultramarines are back, and the four super-soldiers have been joined in their flying city, Superbia, by heroes and reformed villains alike. But now Gorilla Grodd has lured them into a trap.

When someone kills a member of their team, the Maximums, a group of superheroes closely tied to the U.S. government, are on the hunt for the murderer, but the trouble is there are two names on the top of their list: Superman and Batman!