
"What made this the most diabolical murder weapon ever used?"
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.
Mark Lewis

Helen Stephens

Vivian

Mrs. Stephens

Dora

Elderly Gentleman Customer

Arthur Baden

Don Jarvis

Chief Insp. Gregg

Pauline Shields

Milly

Small Man (uncredited)
Shop Assistant on Film Set (uncredited)

Det. Sgt. Miller (uncredited)

Mark's Father - A.N. Lewis (uncredited)

Lorraine the Model (uncredited)

Dr. Rosen

Det. Baxter (uncredited)

Clapper Boy (uncredited)
Young Man in Sports Car (uncredited)

Police Doctor (uncredited)
Publicity Chief (uncredited)
Girl Electrician (uncredited)

Girl in Sports Car Leaving Studio (uncredited)

Miss Simpson - Jarvis' Secretary (uncredited)

Lover in Garden (uncredited)
Lover in Garden (uncredited)
Mr. Peters - News Agent Shop Owner (uncredited)
Young Man Embracing Girl (uncredited)
Mark's Stepmother (uncredited)
Mark as a Child (uncredited)
P. Tate - Studio Cameraman (uncredited)
Mark's Mother on Deathbed (uncredited)
Store Detective (uncredited)
Electrician #1 (uncredited)
Mrs. Partridge (uncredited)

Policeman (uncredited)
Tony - Downstairs Lodger in Lewis' House (uncredited)
Assistant Director (uncredited)

St John's Medic (uncredited)
Party Guest (uncredited)