When a tramp brings what may be a message from his missing father, Michael determines to follow the piecemeal clues and find a boat and crew for the hazardous journey in search of an unknown island located somewhere off the coast of western Ireland.

Before leaving Inishglass, an island off the coast of Ireland, for school in Galway, Dara and Bran visit their tutor who has moved to a haunted island and has plans to keep the boys on the island forever.