In London, a serial killer known as the "Necktie Murderer" has the city in a grip of terror, committing a series of brutal murders where he strangles women with a necktie. The murderer's gruesome modus operandi coupled with his ability to evade capture keeps London on high alert, with the population both fascinated and horrified by the continuing crimes. Public and police are desperate for any leads that might bring them closer to catching the killer, whose actions are unpredictable and motives unclear.

Against this backdrop, Richard Blaney, a down-on-his-luck former RAF pilot turned bartender, finds himself wrongly accused of being the notorious killer after a series of unfortunate coincidences. The real murderer, a friend of Blaney's, cunningly sets him up, leaving Blaney no choice but to go on the run in an attempt to prove his innocence. As he evades the police, Blaney must also seek the true culprit in an effort to clear his name, all the while the real Necktie Murderer continues his spree of terror, leading to a tense and desperate pursuit through the streets of London.