Boris Karloff as David Mallory

Warren Hull as Jim Travers

Jean Rogers as Joan Mallory

Alan Baxter as John Baron aka The Kid

Hobart Cavanaugh as Petty Louie

Samuel S. Hinds as Steven Ranger

David Oliver as Mike Callahan

Ward Bond as Fingers

Frank Reicher as Carl - gang engineer

Edwin Maxwell as Lawyer Kruger

George Cleveland as Sam Adams - Company Engineer (uncredited)

Ruth Fallows as Waitress (uncredited)

George Humbert as Mr. Spinelli (uncredited)

Nina Campana as Mrs. Spinelli (uncredited)

Charles C. Wilson as Police Capt. Wallace (uncredited)

Chuck Hamilton as Policeman (uncredited)