Venom (1981)

In London, the boy Philip Hopkins lives with his wealthy family and collects pets, encouraged by his grandfather Howard Anderson who is a famous hunter. When his mother Ruth Hopkins travels to meet her husband in Rome, Philip stays with Howard, the maid Louise Andrews and the chauffeur Dave. However, Louise and Dave have plotted to kidnap Philip with her lover Jacmel. The plan begins to fail when Philip goes to the pet shop to bring the snake he ordered, and the owner commits a mistake and delivers a dangerous black mamba instead. When the owner of the mamba, Dr. Marion Stowe, receives the pet snake, she learns the mistake and calls the police. One police officer goes to Philip's home and is shot by Dave. Now the police, under the command of the tough Commander William Bulloch, puts the house under siege. Meanwhile, the black mamba is free inside the house and bites Louise who dies.