A villain known as the Whispering Shadow is trying to get his hands on the jewels of the Czar.
...and so is everybody else in this serial thriller. The science fiction aspects are strong here, as the Whispering Shadow uses a radio death ray to deal out death to those who interfere with his plans as well as to project his image from long distances away. The question is; who is he? Is he the well-known horror star who works in a museum known as the House of Mystery, Professor Red Herr...er, Strang? Is it that oily radio technician with the same name as the famous novelist, Steinbeck? Is it the escaped convict who stole the jewels in the first place and wants them back? How about the company president? The company vice-president? Or is it one of the other characters who seemingly appear to be taking little or no interest in laying their hands on the jewels? If you know anything about this type of serial, you should be able to eliminate several of these characters right off the bat. I know I had my guess, but I turned out to be wrong largely because one of the rules I usually apply to figuring out this sort of thing turned out to be incorrect, but I still maintain my guess would have been a good one.
I will admit that this serial was fairly fun, though incredibly confusing; with at least five different people scrambling for possession of the jewels, it leaves your head swimming at times just trying to keep track of who has them. I'm also willing to bet there are some huge plot holes in the story, as I find myself wondering how the actual villain could actually know as much about people's movements as he appears to do. At least you can tell most of the characters apart this time, which helps things immensely.