Hank Davis, foreman on a huge dam project, enlists the aid of his two flyer friends when a sinister figure known as The Black Ace leads his Mystery Squadron of masked pilots in an attempt to destroy the dam.

Texas Ranger tries to stop takeover of Indian lands.

The masked hero leads a fighting force to fight a villian who plots the conquest of The Republic of Mexico.

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?

This 13 chapter serial is based on the comic strip character Ace Drummond created by Eddie Rickenbacker. Ace is a 'G-Man of the sky' working out of Washington D.C. He is sent to Mongolia to find out why a mysterious villain known only as 'The Dragon' is trying to prevent the newly formed International Airways from setting up an airport there. Ace meets Peggy Trainor (Jean Rogers) who is searching for her archaeologist father who has disappeared. Together they search for answers to the puzzles.

Tarzan, who has returned to Africa after living in England, sets off to Guatemala in search of an old friend who may have survived a plane crash there. Also in Guatemala are Ula Vale and Major Martling who are out to find the riches of the Green Goddess. They join forces after they learn that a competitor, Raglan, has already set out ahead of them. Tarzan has to rescue everyone after they are taken prisoner. When they get to the hidden city, Tarzan finds his friend alive and the fabulous treasure.

When his father is killed in a train wreck, Larry Baker vows to unmask a mysterious criminal called "The Wrecker," who has targeted the L&M Railroad for deadly" accidents."

Beyond Hell's Gate Pass is territory controlled by a man who calls himself King Carter; he uses a variety of schemes to prevent the railroad from being built, for fear it will finish his control of (what he considers) his land.

Enemy spies try to steal a new fighter plane.

American adventurer Richard Grant is falsely accused of murdering an Indian noble and escapes to Africa in search of diamond field and the real culprit.