A clan of watermen capture a crew of sport fishermen who must then fight for their lives.A crew of watermen abducts persons in boats to grind their flesh and make bait. Six youngsters have their motor yacht sabotaged and they are stranded in the sea. The crew of a trawler rescues them and they drink spiked water and faint. When they wake up, they learn that they are trapped in an island and they have to fight against the sadistic men to survive.