Detective Fredrik Broman and his family have just moved from Stockholm to Gotland where Frederik is serving his first summer on the Visby police force. Late one night he receives a call from an elderly man complaining about a Volvo with a roof box, that is illegally parked next to a public beach. It smells strange too. Like rotting seaweed. Reluctant, and feeling slightly ill at ease, Fredrik drives to the beach to take a look. The old man was right. There is an unpleasant smell surrounding the car. A quick peek inside the white roof box is enough to explain why. There's a dead man lying inside, or rather what's left of him: he's been butchered like an animal. This sets off a frantic search for a brutal murderer. In the tabloid headlines, the summer island paradise of Gotland turns into "The Island of Horror", and for Fredrik and his family the dream of Gotland becomes a nightmare, as they begin to realise that the horror is right on their doorstep.