Boris Karloff

David Mallory

Warren Hull

Jim Travers

Jean Rogers

Joan Mallory

Alan Baxter

John Baron aka The Kid

Hobart Cavanaugh

Petty Louie

Samuel S. Hinds

Steven Ranger

David Oliver

Mike Callahan

Ward Bond

Fingers

Frank Reicher

Carl - gang engineer

Edwin Maxwell

Lawyer Kruger

George Cleveland

Sam Adams - Company Engineer (uncredited)

Ruth Fallows

Waitress (uncredited)

George Humbert

Mr. Spinelli (uncredited)

Nina Campana

Mrs. Spinelli (uncredited)

Charles C. Wilson

Police Capt. Wallace (uncredited)

Lloyd Corrigan