La scala a chiocciola

Dorothy McGuire

Helen

George Brent

Professor Warren

Ethel Barrymore

Mrs. Warren

Kent Smith

Dr. Parry

Rhonda Fleming

Blanche

Gordon Oliver

Steve Warren

Elsa Lanchester

Mrs. Oates

Sara Allgood

Nurse Barker

Rhys Williams

Mr. Oates

James Bell

Constable

Erville Alderson

Dr. Harvey (uncredited)

Ellen Corby

Neighbour (uncredited)

Myrna Dell

Murder Victim (uncredited)

George Holmes

The Killer's 'Shadow' (uncredited)

Stanley Price

Starry-eyed Man (uncredited)