A Slinking Fiend ... Sulking Terror ... Mad Murder!
Behind the Mask
A Secret Service agent nabs a scalpel-happy doctor who runs drugs in caskets.
Top Billed Cast
Jack Holt
Jack Hart aka Quinn
Constance Cummings
Julie Arnold
Boris Karloff
Jim Henderson
Claude King
Arnold
Bertha Mann
Nurse Edwards
Edward Van Sloan
Dr. August Steiner / Dr. Alec Munsell / Mr. X
Willard Robertson
Capt. E.J. Hawkes
Thomas E. Jackson
Agent Burke
Martha Mattox
Hotel Ansonia Maid
Jessie Arnold
Eastland Hospital Nurse
Harry Tenbrook
Man in Black / Henchman in Boat
