Anna Massey

At Oxford University, a professor and a grad student work together to try and stop a potential series of murders seemingly linked by mathematical symbols.

London is terrorized by a vicious sex killer known as The Necktie Murderer. Following the brutal slaying of his ex-wife, down-on-his-luck Richard Blaney is suspected by the police of being the killer. He goes on the run, determined to prove his innocence.

Loner Mark Lewis works at a film studio during the day and, at night, takes racy photographs of women. Also he's making a documentary on fear, which involves recording the reactions of victims as he murders them. He befriends Helen, the daughter of the family living in the apartment below his, and he tells her vaguely about the movie he is making.

Trevor, an insomniac lathe operator, experiences unusual occurrences at work and home. A strange man follows him everywhere, but no one else seems to notice him.