The human race is threatened by a powerful creature, and only the combined power of Superman, Batman, Wonder Woman, Green Lantern, Martian Manhunter and The Flash can stop it. But can they overcome their differences to thwart this enemy using the combined strength of their newly formed Justice League? In the 1950s, a new generation of superheroes must join forces with the community's active veterans and a hostile US government to fight a menace to Earth.