Marine biologist Dr. Mason Rayman is experimenting with gigantism in sea creatures when he accidentally creates a monstrously large sawfish. When it grows so big he can no longer keep it in his Miami lab, he is preparing to have it destroyed when he learns he is being terminated from his position. By way of revenge, he dumps the oversized shark relative into the ocean, where it soon roams out of control, slaughtering bathers at nearby trendy South Beach. Dr. Rayman doesn't let on that it's his fish responsible for the killings, but someone knows what he did, and she's blackmailing him. He plays along for a while, but then decides she needs to be eliminated. Breaking into a lab at his former workplace, he deliberately creates more monster sawfish and releases them into the local waters. Rayman then attempts to get his job back by stepping forward as the expert on how to stop the scourge of gigantic predators now ravaging swimmers and water sports enthusiasts on South Florida beaches. But his blackmailer will not let up, leading to an ultimate confrontation between woman and beast, and finally, woman and man.