Whales are dying on the Scottish coast and cetologist Sarah Bennett wants to know why. Something is attacking and killing these mighty leviathans. Something voracious. The source of the dead whales seems to be the sleepy fishing isle of Mol Mar, where police sergeant Maurice Bradley is investigating several bizarre killings, the victims left drained of blood. With Sarah's help, Bradley discovers the deaths of the islanders and the whales are inextricably linked, and the pair soon find themselves battling a terrifying blood sucking menace from the sea, intent on devouring the island's inhabitants.