A big black mamba snake that has gotten loose in a townhouse slithers through a kidnapping plot in this film. Based on a novel by Alan Scholefield, features a big name British cast that seems to be slumming in a B-movie project. Dr. Marion Stowe (Sarah Miles) is a toxicologist who has brought the snake to London to study the properties of its deadly venom. It escapes and terrorizes the inhabitants of the townhouse, where an attempted kidnapping is in progress. Dave (Oliver Reed), Jacmel (Klaus Kinski) and Louise (Susan George) are the villains trying to hold the son of a wealthy family for ransom. Original director Tobe Hooper was replaced by Piers Haggard. ~ Michael Betzold