John Christie (Richard Attenborough) has agreed to sublet his upstairs London flat to Timothy Evans (John Hurt) and his pregnant wife Beryl (Judy Geeson). After they move in, John reveals to the couple that he is an accomplished abortionist and would be happy to help them perform the illegal operation to help them out of their jam. However, John becomes aroused by Beryl's naked and unconscious form, and he rapes and strangles her. Afterwards, he convinces Timothy that Beryl died during the normal course of the surgery. John flees when he thinks that he will be convicted of murder. Will the police be able to find and arrest John Christie before he strikes again?