 Jack Foster (Malcolm McGregor) is searching for the killer of his brother Bud (George J. Lewis.)The trail leads him to the House of Mystery, a waxworks, where the mysterious and somewhat sinister Professor Adam Strang (Bela Lugosi)makes wax figures that move and speak with lifelike precision. Each time one of the radio-equipped trucks of a huge moving-and-storage company transports one of Strang s figures, its driver is attacked and killed by the henchmen of "The Whispering Shadow." Each holdup is preceded by the mysterious jamming of the bradcasting equipment in the radio room atop the warehouse. No man has ever seen the Shadow, but his genius for manipulating radio and television enables him to project his voice and shadow where ever he desires; he can see through doors, hear through walls and electrocute people by radio death ray. His quest is to acquire the priceless jewels secretly stored in the transport warehouse. Foster s list of suspects include Professor Strang; Alexia Steinbeck (Roy D Arcy),a mysterious Russian in charge of the radio room; Jerome (Lafe McKee), a company official who wanders in and out of the radio room at all hours of the night; and Jasper Slade Bob Kortman), an escaped comvict and internationally-known jewel thief. Is "The Whispering Shadow" one of these men, or none of the above?