After a peaceful sailboat ride, four young people, including rich kid Bill, Joe, Fred and Jane, knock on the door of a secluded villa after their dune buggy runs out of gas. Earlier in the day, Bill had given the lovely Jane a pearl necklace with a supposedly paranormal history, and this later opens up a can of worms. They are invited to spend the night at the mansion, owned by Lord Alexander and Lady Alexander, who happen to be hosting a strange ceremony that night attended by a group of eccentrics in black robes. During the evening, Jane exits her sleep chamber, seemingly in some kind of trance, and is lured to a sacrificial alter where the robed houseguests are hovering over her. As a knife is about to be plunged into the young lady, her three friends come to the rescue, but they are also witness to a chaotic mass murder catastrophe in which they flee with feelings of guilt and uncertainty.

Secret Agent Francis Coplan, is given the task of finding priceless artwork stolen by the Nazis' in 1943. The trail leads to Mexico, where Coplan challenges a "secret" organization in order to re-gain the paintings.