A crime fighter known as The Spider battles a villain called The Octopus, who is out to sabotage America and install his own government.

The California-Yucatan Railroad, being built for the good of Mexico, is under siege by a gang of terrorists hoping to force its sale; no one can prove their connection to profiteer Marsden. Manuel Vega, aged co-owner, calls in the aid of his nephew James, great-grandson of the original Zorro. Alas, James seems more adept at golf than derring-do; but after he arrives, Zorro rides again! Can one black-clad man on horseback defeat a gang supplied with airplanes and machine guns?

Secret Service Major Steel (Joseph W. Girard), is one of the few men in America aware of the fact that Captain Albright (Dave O'Brien) is also Captain Midnight, daring masked aviator dedicated to fighting gangsters and enemies of America. When murderous bombing attacks are made on West Coast munitions plants, Steel sends for Albright and asks him to track down the mysterious Ivan Shark (James Craven), the foreign agent mastermind behind the attacks. Shark has learned about an ingenious range finder, invented by John Edwards (Bryant Washburn, and makes plans to obtain a model of the invention. Edwards instructs his daughter, Joyce (Dorothy Short), to bring the model to Albright for safekeeping in his mountain laboratory. Shark takes Edwards prisoner by Albright assures Joyce that her father will be saved and an end put to Shark's reign of terror. Dressing as Captain Midnight and enlisting the aid of his friends, Chuck (Sam Edwards) and Ichabod Mudd (Guy Wilkerson), Captain Midnight delivers on his promises fourteen chapters later.

New York City policewoman Casey Jones' assignment to fight crime often entails her going undercover in some of the seediest and most dangerous parts of the city.

The period is the 1820's and the first wagon train leaves Independence heading west to Santa Fe. In order to maintain his power, the ruthless Official at Santa Fe must not let them arrive and he sends out his men to stop them. The wagon train then has to endure repeated attacks but is aided by a mysterious rider that shoots singing arrows and rides a painted stallion.

In this Western, comprised of 12 chapters from a serial, Kit leads a group carrying a large gold shipment across the wild West. When the Mystery Riders attack and steal the gold, Kit is the only survivor. He later joins forces with the cavalry to retrieve it.

Captain Dan Tempest was an ex-pirate who received a pardon from the King and turned privateer after his stronghold of New Providence was taken over by Crown soldiers. Tempest and Lt. Beamish, the Crown-appointed deputy governor, were uneasy allies, fighting the Spanish privateers who were ravaging the Caribbean.

The Eagle uses sky writing to make threats against a corporation. Nathan Gregory owns a traveling fairground and is thought to be the Eagle. Craig McCoy is a pilot who goes looking for the Eagle when Gregory turns up missing.