This may be the end of all Earths. The Monitor has called upon a group of champions to save all of reality: Batman of Earth Prime, Wonder Woman of Atomic Earth, Mecha-Superman K.A.L., and even Gaslight Lex Luthor—brought together to stop a mysterious foe from destroying their homeworlds. But this unseen villain has only one real target: Nil, the very axis of the multiverse!
As the multiversal heroes race to defend the Monitor's stronghold, new threats are never far behind. Someone has installed Earth Engines on nearly every Earth in every universe—if activated, they could destroy each world from within. The hope is to shut down the devices before disaster strikes. Fortunately—or unfortunately—for them, it seems that someone with intimate knowledge of the Engines is already amongst their ranks. But does his inside knowledge point to a secret past?