A nature-phobic scientist, a Fish and Game Warden, a sheriff and an eccentric mythology professor converge near a remote lake in Maine to investigate a gruesome fatality. Their adventure, laced with humor and terror, leads to a shocking secret that waits underneath the anything-but-placid waters. The only evidence in the watery death is a large, seemingly prehistoric tooth found at the scene. Intrigued by the discovery, yet smarting from a recently botched office romance, an emotionally fragile paleontologist, Kelly Scott is reluctantly dispatched for her first real field assignment. Scott's big-city manner and obvious distaste for the great outdoors is a constant irritant to the man in charge of the inquest, Fish and Game Warden Jack Wells, who would prefer not to be burdened with her help. Also on the scene is the irascible, overly sensitive sheriff Hank Keough, who would like nothing more than to find the predator and blow its head off. Landing unannounced in the middle of the action is the rich, eccentric mythology professor Hector Cyr (Oliver Platt), who steamrolls the team into trying to capture and preserve the elusive creature that appears to be lurking nearby. An exhaustive search leads them to the only full-time resident on the lake, a scatter-brained old woman, Mrs. Bickerman, who withholds information surrounding the mysterious disappearance of her husband and some of her missing livestock. But it isn't long before the lake's incredible secret is revealed to all.