The Secret Code - Paul Kelly (1942) is a 15 Chapter movie serial released by Columbia Pictures.
It features the masked hero "The Black Commando" (Paul Kelly) facing Nazi saboteurs, inspired by Republic Pictures' successful Spy Smasher serial of the same year. The chapters of this serial each ended with a brief tutorial in cryptography.
This serial takes place during World War II, when a superhero (The Black Commando) tries to prevent Nazi agents from stealing a secret formula. The spy ring is led by fifth columnist Rudy Thyssen (Robert O‘ Davis), who is trying to get possession of this top-secret formula the United States had developed for manufacturing synthetic rubber. Then, Police Lieutenant Dan Barton (Paul Kelly) stages a public dismissal from the police department, in order to join the saboteurs and learn their secret code they have been using, creating explosive gases and artificial lightning to sabotage the exhausting war effort. To further assist his efforts, Barton assumes the secret identity of the Black Commando, a masked man who is wanted both by the villains and police, who (allegedly) are also searching for Barton for a murder charge.