When Sparks (Karl Dane) reports a continuous bleeping of coded messages coming from Steinbeck's private laboratory, Vice-President Jerome, Detective Raymond, and Jack Foster investigate. Professor Strang is also lurking in the warehouse to retrieve the key for the safety deposit box in which the jewels are hidden! It is time for Jack Foster to come face-to-face with the Whispering Shadow! (1933 - Mascot Pictures)
