Offshore near Caboblanco, Peru, an explorer of sea wrecks is murdered. However, local authorities decide that the official cause of death is "accidental drowning." Among the skeptical is Giff Hoyt (Charles Bronson), an expatriate American, longtime Caboblanco resident and popular innkeeper. Giff's interest is further piqued when Marie (Dominique Sanda) arrives in town. Her passport is confiscated by the corrupt authority (Fernando Rey), and Giff protests. Furthermore, a Nazi named Beckdorff (Jason Robards) lives in a well-fortified compound near town, and he might be responsible for the explorer's death. Beckdorff himself seeks sunken treasure in the area, as well as protection from local interference. Can Giff Hoyt stifle the evil Beckdorff, save the lovely Marie, and possibly even locate sunken treasure?