While on the Justice League's orbiting Watchtower, an alert of dual emergencies in Gotham City calls Batgirl and Supergirl into action. They step into the teleporter. In the same moment, something attacks and damages the Watchtower's tech.
When Batgirl and Supergirl investigate mysterious tremors in Gotham Bay, they dive underwater and discover... Lex Luthor! The crooked businessman is running a mining operation to dig up deep-sea Kryptonite deposits.
When a weird, wild wail echoes from the Metropolis Museum, Batgirl and Supergirl rush inside ready for a fight. But all they discover are groggy workers-and one ancient tome missing from a rare book exhibit.
