Peeping Tom

Loner Mark Lewis (Carl Boehm) works at a film studio during the day, and at night takes racy photographs of women. However, he also is filming a documentary on fear, which entails recording the reaction of his victims as he murders them. He becomes friends with Helen (Anna Massey), the daughter of the family living below, and he tells her vaguely about the film he is making. When she sneaks into Mark's apartment to watch it, she is horrified by what she sees -- especially when Mark catches her.