Prior to the United States' involvement in World War II, the masked vigilante Spy Smasher fights Nazi agents operating within the US, led by the treacherous sabotage leader codenamed The Mask.
Judge Kirby is being blackmailed and forced to let outlaws go free. He was once the partner of Roy's father and when Roy reads in the paper that he is in trouble he heads out to help him. Arriving, Roy quickly realizes he has been mistaken for one of the outlaws and is not wanted in town. However he stays, and now posing as that outlaw, hopes to learn who is causing all the problems.
A Nazi spy ring is after a chemical formula that increases the power of ordinary gasoline for U.S. Army aviation use. Two U.S. chemical companies are developing the formula, with each working on half for security purposes. The spies get half the formula and know that either of two chemists, Robert Norton or Tom Fielding, knows the rest. They capture Fielding, through a ruse by gang member Linda Pavlo, and threaten the life of his sister Nancy and his mother if he does not give them the formula. To protect his friend Fielding, who does know the formula and is engaged to Nancy, Tom pretends to know the secret and boards the Dawn Express plane with the spy leader and his gang.
The Mesquiteers return to Texas after the Civil War to find Army carpetbaggers fighting the local bushwackers. They quickly learn that Capt. Hawks and his men are the culprits and join up with Morgan and his men.
A scientific expedition happens to discover that gold exists on Tarzan's escarpment. The villainous Medford and Vandermeer kidnap Jane and Boy to extort from Tarzan the location of the gold.
An expedition sets out to darkest Africa to find the fabled City of the Dead, and must battle thick jungle, hostile natives, wild animals and a deadly epidemic.
The Rough Riders are called in to help save Master's stage line. Taggart has his gang robbing the stages and shooting the drivers. When Buck drives the next stage, Taggart's men rob it and then make it look like Roberts is part of the gang. Written by Maurice Van Auken
The story concentrated on a group of test pilots, busily experimenting with a revolutionary all-plastic airplane. Ace flyboy Brad Farrell (Richard Arlen) is determined to prove the practicality of the new aircraft, designed by Professor Blake (Thomas Ross), father of Brad's sweetheart Carol (Jean Parker). Back on solid ground, Brad must vie for Carol's attentions with his own brother, engineer Doug Farrell (Don Castle).
The mayor has sent for a gunslinger who, though appearing to clean up the town, is really to be the mayor's means of taking the town over. When Roy and Gabby arrive in Tombstone, Roy is mistaken for the gunslinger. Just as Roy is ready to expose the mayor, the real gunslinger shows up.
Roy is a newspaper reporter. He goes to Cheyenne to cover the activities of supposed bad guy Arapahoe Brown. Roy, of course, discovers who the real bad guy is.
When the showboat hits town, two men use the parade as a distraction to rob the bank. Their accomplice is Pop, the clown from the showboat. He leaves the money on the boat and tells his daughter Patsy to bring it to him at a later stop on the river. Gene's investigation of a bank robbery takes him to the showboat where he becomes a performer. Gene and Frog try to find the money while helping Patsy and her father.
Muggs is tricked into entering a Civilian Conservation Corps camp by Danny in order to get in shape. Muggs resists and battles with the camp captain and with other campers. He also becomes involved in trying to help one of his friends get out of trouble.
Rightful owner of the kingdom, the Duchess of Zona, is engaged in a power struggle with the evil General Gurko. Edmond, the son of Monte Cristo, dons many disguises to come to the aid of the Duchess.
Wanted by the law in New York, Dr. Steve Kells heads west and arrives in an area controlled by an outlaw gang known as the Border Legion. When the gang's boss is wounded, they kidnap Kells and force him to remove the bullet. Not allowed to leave and being a wanted man, he joins the gang. Now wanted as a gang member also, he nevertheless plans a raid that will lead the entire gang into a trap.
In 1820 Spain, the son of a California nobleman comes home to find his native land under a villainous dictatorship. On one hand, he plays the useless fop, while on the other, he is the masked avenger Zorro.