Mason Moonbiker and his sister Marvel’s frog-catching days in their nearby swamp are over, but not because Hurricane Daphne swept the prize amphibians away—they all simply vanished.

One more attempt at catching frogs before summer’s close means an evening trip into the abnormally silent swamp. But the horror the siblings discover begins to unravel a mystery that threatens to devour all they hold close in their cozy island town. 

Mason, Marvel, and Georgina have come face-to-face with the gruesome aquaclownbies inhabiting the swamp. But where did the creatures come from? Who’s responsible? And how do they find out without endangering Grandma T?

The threat is growing and time is running out. Can the children find a way to work together to unmask the menace in the swamp before it’s too late?