Summer on the beautiful Swedish island of Oland. Visitors arrive in their thousands, ready to enjoy the calm and relaxation of this paradise. Amongst them is Jonas Kloss, excited at the prospect of staying with his aunt, uncle and older cousins. But it is not as he had hoped. One night he takes a boat out onto the moonlit sea. A ship looms out of the darkness and the horror he finds on board is unimaginable.Fleeing for his life, Jonas arrives at the door of an elderly islander, Gerlof Davidsson. Once Gerlof has heard his tale of dead sailors and axe-wielding madmen, he realizes that this will be a summer like none other Oland has ever seen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .