""The Unknown" was the final entry in Columbia’s I Love A Mystery series. A woman hires two detectives to keep her alive long enough to claim her inheritance."
Karen Morley
as Rachel Martin
Jim Bannon
as Jack Packard
Jeff Donnell
as Nina Arnold
Mark Roberts
as Reed Cawthorne (as Robert Scott)
Robert Wilcox
as Richard Arnold
Barton Yarborough
as Doc Long
James Bell
as Edward Martin
Wilton Graff
as Ralph Martin
Helen Freeman
as Phoebe Martin
Robert Kellard
as James Wetherford (as Robert Stevens)
J. Louis Johnson
as Joshua (uncredited)
Dwight V. Babcock
Adaptation
Henry Levin
Director
Carlton E. Morse
Radio Play
Charles O'Neal
Henry Freulich
Director of Photography
Mischa Bakaleinikoff
Music Director
George Brooks
Art Direction
Wallace MacDonald
Producer
Malcolm Stuart Boylan
Screenplay
Julian Harmon
Art Seid
Editor
George Montgomery
Set Decoration