With customary lack of restraint, Bela Lugosi tore into his role of Professor Strang, a foreign agent masquerading as a wax museum proprietor, in this the first of Mascot Pictures' five serials of 1933. Bela is smuggling jewels into the country as security for a loan. The "jools," however, are stolen by an escaped convict and sought by the omnipresent Whispering Shadow, a mysterious megalomaniac out to gain control of the entire world. A science wizard, the Shadow uses radio waves to kill his enemies, but no one knows who he is. In typical Mascot fashion, suspicion falls at various times on most of the cast members -- Lugosi, needless to say, most of all. As it turns out, despite a plethora of menacing close-ups, Bela is indeed only a red herring, the real culprit, in typical Mascot style, revealed instead to be a heretofore minor comic relief. Considering the fate of the actor in question, we shall break with tradition and name him. A major comic star of the late '20s, Karl Dane could only watch as his career collapsed at the changeover to sound due to an impenetrable Danish accent. All but unemployable, Dane was given this last chance to shine by producer Nat Levine, but audiences felt cheated by the serial's somewhat unfair denouement and The Whispering Shadow proved less a comeback than a debacle. Reduced to selling hot dogs from a stand outside his former studio, MGM, Dane ended his own life on April 14, 1934, one of the best remembered victims of the sound revolution. The Whispering Shadow marked the directorial debut of Colbert Clark, formerly of the script department, who was helped along the way by the veteran Albert Herman. The serial was also released in a truncated feature version.