Feeding frenzy

"Time has passed since anyone's heard from Dr. Catalyst. Emmet and Calvin have even begun to think that the crazed scientist might be gone for good. But then, on a trip to snorkel off the Florida coast, one of their friends is nearly drowned by an underwater monster with endless rows of razor-sharp teeth. ... Dr. Catalyst is back. And this time, he's out for revenge"--Back cover.