Discover
Ralph Bellamy
Ellery Queen
Margaret Lindsay
Nikki Porter
Charley Grapewin
Insp. Queen
James Burke
Sgt. Velle
Michael Whalen
Dr. James Rogers
Marsha Hunt
Barbara Braun
Fred Niblo
John Braun
Charles Lane
Dr. Prouty
Ann Shoemaker
Lydia Braun
Marion Martin
Cornelia
Douglas Fowley
Rocky Taylor
Morgan Wallace
Zachary
Byron Foulger
Amos
Katherine DeMille
Valerie Norris
Peter Bronte
Doctor's Assistant (uncredited)
Jack Cheatham
Desk Sergeant (uncredited)
Arthur Millett
Elevator Guard (uncredited)
Frank O'Connor
Ambulance Driver (uncredited)
Lee Phelps
Flynn (uncredited)
Jack Rice
Rogers' Assistant (uncredited)
Alan Ladd
Elevator Passenger (uncredited) (unconfirmed)
Camera
James S. Brown Jr.
Director of Photography
Directing
Kurt Neumann
Director
Camera
James S. Brown Jr.
Director of Photography
Directing
Kurt Neumann
Director