A young girl journeys to Africa to find her father, an explorer who vanished in the jungle.

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.

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.

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?

Dr. Herbert Lee (John Paul Jones), an archaeologist seeking to decipher ancient Mara inscriptions, is aided by his son, Terry (William Tracy), and Terry's pal, Pat Ryan (Jeff York), and Normandie Drake (Joyce Bryant). Fang (Dick Curtis), a jungle pirate and warlord,plots to kill The Dragon Lady (Sheila Darcy), Queen of the Temple of Mara, and seize the treasures of her ancestors. Both Fang and The Dragon Lady have sworn death for any foreign intruders.

Professor Davidson and his niece Diana Palmer search Africa for the Lost City of Zoloz, reputed to be the source of a large hidden treasure. Also searching is a local crook, Singapore Smith, and Dr. Max Bremmer, who plans to destroy the peace in which the native tribes have been living. However, Godfrey Prescott, otherwise known as the Phantom, is feared and respected by the natives and is able to circumvent the traps and schemes of the villains.

Texas Ranger tries to stop takeover of Indian lands.

A newspaper publisher and his Korean servant fight crime as vigilantes who pose as a notorious masked gangster and his aide.