In an alternate world Superman has not only mistakenly killed his wife Lois Lane and their unborn son, but destroyed Metropolis with a nuclear bomb. When it was discovered by Superman that Batman's enemy: The Joker was the mastermind behind Superman's mistake by drugging him. In retribution Superman kills The Joker. In the real world The Justice Leafgue fights the Injustice League in metropolis and the Justice League Watchtower. As The Joker and his girlfriend Harley Quinn set a nuclear bomb in Metropolis, most of the Justice League members and The Joker were teleported to the alternate world where Superman is the oppressive ruler of the Planet Earth and where that world's Batman is a rebel trying to topple the empire. The real world's Justice League must team up with the alternate world's Batman and end the alternate Superman's empire...