Filmmaker and photographer Mark Lewis (Karl Heinz Böhm) spends days searching for just the right female models for his films which are studies of fear. He was raised by a psychologist father who used Mark as a subject for his own studies of fear and the exposure has left him marked psychologically so that he now is compelled to continue his search for women he murders for the camera as he films their reactions. Mark lives in the upper floors of his family house where he also has his photo lab and rents the downstairs to Helen Stephens (Anna Massey) and her blind mother Mrs. Stephens (Maxine Audley) whom he avoids until one day on Helen's birthday when the young nubile girl introduces herself to the photographer and they feel a connection. Mark trusts Helen enough to show her the films that his psychologist father took of him as a boy and the images disturb the girl but draws her closer to Mark. Mark's jobs as studio camera man for a film studio and cheesecake photographer for a local photo shop allows him easy access to women whom he murders while photographing to show their reactions to fear. When Helen accidentally sees some of his killing films she is appalled but wants to help Mark but the release of his secret is too much to bear as the police close in.
To whom does Mark begin to feel a real connection?
Helen Stephens