The son of a psychologist develops a fetish for murdering women and recording their final death throes on film, a twisted and gruesome version of his father's own voyeuristic experiments in which he recorded his son obsessively throughout every moment of his childhood. Michael Powell's psychological thriller, starring Carl Boehm, Anna Massey and Moira Shearer, and featuring the late Nigel Davenport.

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.