The Mysterious Pilot

Evil Hassan slips back into his native land of Ahad and plots to overthrow his twin bother, Kasim, who has just been crowned the Caliph. Hassan enlists the aid of the chief Chamberlain, Faud and they send several henchmen into the royal palace, who then knock Kasim unconscious. Faud and Hassan dispatch a couple of different hirelings to take Kasim into another part of the town and murder him.Kasin comes to and gets away, but has been wounded. Omar, a beggar, takes Kasim to his home and nurses him back to health. But, it takes a few weeks for Kasin to get healthy and, by that time, Hassan has a firm grip on the duties of a Caliph. In a storeroom, Kasim finds a coat of mail with a great hawk emblazoned across the chest and promptly decides this is the costume he will wear while fighting to get his old job back. Meanwhile, the Emir of Telif shows up with his daughter, Princess Azala, with the intent of marrying her off to the local Caliph.

An accomplished aviator sets out to locate treasure hidden by one of his ancestors. He encounters interference from various adversaries.

An escaped criminal impersonates a Police Commissioner, causing no end of trouble to a determined Federal Agent.

Greedy traders have kidnapped a researcher, hoping he will reveal the location of a treasure in a hidden village. Family and friends of the researcher come looking for him. Adventure ensues.

A team of two-fisted insurance investigators (one of whom disguises himself as The Masked Marvel) endeavor to discover and thwart the loathsome saboteur Sakima.

Congo Bill is hired to locate an heiress lost somewhere in Africa.

A Martian invader crashes his spaceship conveniently close to the workshop of a scientist who is developing an interplanetary craft. If the extraterrestrial Purple Monster can complete the rocket ship and return to Mars, he will be able to start a full-scale invasion of Earth. Good thing Craig Foster sets out to thwart the Monster's mission!

Claire Forrest seeks her kidnapped scientist father, hidden somewhere on Mystery Island. He is held and forced to work on diabolical inventions by Captain Mephisto, a costumed villain.

Man-woman team of investigators uncover a gang whose mad scientist leader has developed an invisibility chemical and plans to build a mercenary army of invisible men.

A famous scientist invents a humanoid robot (the titular "monster"), so a greedy rival scientist plans to steal it for use in his criminal plans. His henchmen often kidnap a trained gorilla (the titular "ape") from the zoo, to aid in the schemes.

Daniel Robin has become mixed up with a band of criminals known as "the 13," and is shot when he refuses to do their bidding. His daughter Ruth, brought home from boarding school, reaches his bedside before he expires. He tells her that she will be given thirteen keys. Instructions will be provided with each key and, if she follows the instructions, she will eventually fully learn of her birthright. Many adventures then follow as Ruth attempts to solve the puzzle of each key and establish her true birthright.