A Scotland Yard detective is investigating a string of robberies and a murder, and the information he uncovers leads him to the estate of a wealthy but strange English family, who share their mansion with a group of nuns. The detective comes to suspect that neither the family nor the nuns is quite what they seem to be

Although filmed by a joint German-Yugoslav crew, this European western is set in the Southern United States and involves an oddly-named hero, Old Shatterhand (Lex Barker of Tarzan fame). O.S. has a sidekick, Winnetou, an Apache chief played by a rather understated Pierre Brice. The fuel behind the drama is a hidden map…