A bunch of waterfront youths pursue the Sea Raiders, a gang of saboteurs.
An escaped criminal impersonates a Police Commissioner, causing no end of trouble to a determined Federal Agent.
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.
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.
Jerry Blake (aka Federal Operator 99) teams-up with Joyce Kingston to thwart the plans of escaped crime boss Jim Belmont.
An expedition arrives on an uncharted jungle island to rescue the local natives, led by a jungle boy, from a volcano that is about to erupt.
Escaped Prisoner 39013 impersonates the rich and influential Horace Granville, allowing him to create a variety of disasters. Fortunately, he is thwarted repeatedly by three daring circus daredevils.
A police detective is caught up in a plot to steal two million dollars in bonds.
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.
Mystery and adventure, surrounding a stolen rubber harvest.
Four flying G-Men protect America against enemy spies; one of the four assumes the identity of The Black Falcon, to befuddle the saboteurs even further.
Pulp hero "The Spider" seeks to destroy all criminals. In this serialized adventure, he battles The Octopus, who intends to replace the government of the United States.
Mandrake and his team attempt to prevent "The Wasp" from stealing and using a new Radium invention.
Jesse James wants to start a new life in a new location, but quickly finds himself wrapped-up in protecting townsfolk from the machinations of evil oilmen.
A cult of Hindu tiger worshippers and a gang of Western outlaws try to cheat a young woman out of rich mines that belong to her.
Beatrice Fairfax, the original advice-to-the-lovelorn reporter and her friend and not-so-secret admirer Jimmy Barton investigate calls for help and escape exotic perils and dangers. Episodes include exciting and fun stories of baby-napping, blackmail, jewel thievery, disguise, counterfeiting, and the long-unseen episode featuring entrancing cult starlet Olive Thomas and the real New York Yankees and Giants playing a game in the Polo Grounds.
Richard Grant, imprisoned in India for a crime he did not commit, escapes and makes his way to Africa.