Batman and Superman team up to deal with an alien invasion, and a telepathic message leads the duo to a military base housing future ally J'onn J'onzz.
The heroes are captured by the aliens just as their leader, the Imperium, arrives. After vanquishing the invasion, they decide to officially join forces as the Justice League.
Suspecting a railroad job, the League digs deeper into the charges against the Lantern. When the Guardians of the Universe arrive, the Manhunters' true motivation is revealed.
The team encounters an agitated Aquaman while trying to rescue a submarine crew. His opinion of surface dwellers doesn't improve after an attempted assassination by Deadshot.
The team is captured after helping Aquaman stop an underwater coup by his half-brother, Orm. Struggling to free himself and his son from death, Aquaman sacrifices his own hand.