Set in the early 1970s, the plot centres on a serial killer terrorizing London by raping and then strangling women with a tie. Bob Rusk (Barry Foster (actor)), a Covent Garden wholesale produce merchant, is the murderer. However, circumstantial evidence, partially engineered by Rusk, will implicate Rusk's friend Richard Blaney (Jon Finch), who becomes a fugitive attempting to prove his innocence.