Venom

“The kidnap that became a murder, that became a siege, that became a death trap.”

Jacques Müller (Klaus Kinski) and Dave Averconnelly (Oliver Reed) plan to kidnap the child of a wealthy couple and hold him for ransom. Piers Haggard keeps the plot to a single night, with the hostages, the kidnappers and a Black Mamba shut up together in one house. Nobody inside it has any control, and the plan the kidnappers made no longer matters.