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.

When an American tourist is murdered in the south of France, the police must investigate. In this movie, the police inspector re-creates the girl's journeys through France until the murder is solved. Suspicions are narrowed down to four possible perpetrators early on, and flashbacks illuminate the roles each one played in the girl's vacation.

A Texan sheriff and his younger brother travel across the border into Mexico to confront the man who killed their father.