A group of rich Italians head out on a yachting trip to a deserted volcanic island in the Mediterranean. When they are about to leave the island, they find Anna has gone missing. Sandro, Anna's boyfriend, and Claudia, Anna's best friend, try without success to find her. When they get back to land, they continue the search with no success. Sandro and Claudia proceed to become lovers, and all but forget about Anna.