A few years before he went on to make a big splash in the cannibal sub-genre, Ruggero Deodato directed this successful rip-off of Roman Polanski's brilliant Knife in the Water. Naturally, being an Italian film - there's more of a focus on sex than the relationship between the central couples, but the claustrophobic atmosphere and entertaining characters help to keep the tension bubbling over, which ensures that the movie is interesting for the duration. The film doesn't have nearly as much 'bite' as Cannibal Holocaust and most of the rest of Ruggero Deodato's filmography, but it's obvious that even with this early film; Deodato is a director with the potential to make a mark on cinema. The plot is simple in that it just focuses on two couples. George and Silvia invite Irem and Barbara for a weekend cruise on their yacht. It soon transpires that George isn't the most sensitive man to ever live, and Silvia doesn't seem to mind him treating her badly. The situation escalates, and Irem and Barbara join forces with Silvia for vengeance against George...and three way sex, of course.