Six members of the seven “Emotional Spectrum” Lantern Corps are all summoned by a mysterious force, revealed to be Brainiac. The Corps are defeated and brainwashed into serving him. With this complete, Brainiac charts a course for Earth in order to retrieve someone from the Green Lantern Corps – the Lantern Corps he still needs. Namely: Hal Jordan. Meanwhile, in Gotham City, Batman and Robin pursue Killer Croc through the sewers. Croc escapes and hands over a map to his accomplices: the Joker, Cheetah, Firefly, and Solomon Grundy. At the Hall of Justice, Cyborg completes work on a “Slideways Teleporter” linking the Hall of Justice to the Justice League Watchtower and sends Green Lantern through it to meet with Martian Manhunter as a trial run. The test is successful, and the portal is left open.
Back at the Batcave, the Batcomputer detects Brainiac’s approaching spaceship. Observing it via telescope, Batman is exposed to the mind-control ray and goes berserk, laying waste to the Batcave and trying to escape via the Batmobile. However, the car’s defense system electrocutes him, giving Robin enough time to talk Batman out of his trance with a heartfelt speech; however, Batman maintains it was the electricity, and not the speech, which woke him. At the Hall of Justice, the Joker and company break into the Slideways Teleporter room via the sewer using the map Croc stole and are joined by Lex Luthor disguised as Hawkman, having locked up the real Hawkman. Luthor is revealed to be the mastermind of the scheme, planning to use the Watchtower’s binary fusion cannon to hold the Earth at ransom and force the citizens to make him President. The group enter the teleporter.