P.C. McPhee is in Australia to help his uncle solve an underwater mystery involving buried treasure. P.C. quickly figures out that they're not the only ones looking for treasure -- an evil geologist is determined to get her hands on it at any cost. P.C., his uncle, and the Aboriginal girl, Maruul; become ensnared in a deadly game of cat and mouse where the winner takes all, including the lives of the losers.