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.
But as the two friends battle Luthor and his drones, the green dust that
fills the cavern quickly drains Supergirl's superpowers. What's worse,
the unstable tunnels are at risk of total collapse! Can the girls shut
down the Super-Villain's Kryptonite collection scheme before they get
trapped beneath the waves? Find out in this action-packed, illustrated
chapter book that's perfect for young DC Super Hero fans!