Murray Dae, the Chief Officer of Leaks, is two days from his retirement when the biggest leak of his career—and the history of the Great Green Lake—strikes the Half Lake Inn. The Pon Pon flower shop has four terrifying leaks, caused by a family of Wood Fish... Murray and his staff race toward the impending catastrophe in the Leaks Agency's submarine, the Onyx,, taking a dangerous shortcut through the Valley of Bones, guarded by the colossal turtle Baugmaus. Will they outrun the leaping leviathan, or end up like the beast's countless victims piled high in the canyon? If so, will they be able to save the Inn, which is filling with water at a terrifying speed?