On a Californian beach, youngsters find a savaged whale carcass with teeth marks ten feet across. Even having seen Jaws, the authorities are temporarily baffled as to what creature might be the possessor of this leviathan mandible. Marine biologist Spencer Northcutt (Antonio Sabato Jr.), rugged and interesting, is called in to get to the bottom of this unlikely conundrum. Soon he digs out a shark tooth nine inches across and at once the mystery is solved and the business of being mightily afraid begins. The only creature ever to possess such gigantic incisors is, it is said, the Carcharodon Megalodon - a prehistoric sharkish entity - thought long extinct.