Flash Gordon, Dale Arden and Dr. Zarkov return to the planet Mongo for an antidote to the Purple Death, which wreaking destruction on Earth. However, Ming the Merciless has other plans for them.

A military intelligence officer and a pretty reporter try to find a scientist whose inventions can destroy the world.

A mysterious criminal known as The Whispering Shadow commits crimes by means of a gang he controls by television and radio rays. Jack Norton, whose brother was murdered by The Whispering Shadow, suspects that the eerie Professor Strang - whose ghostly wax museum contains figures far too lifelike - may be involved in the crimes.

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.

Strategic targets on Earth are being destroyed by an unknown weapon. Government security head Henderson suspects it's an "atomic ray" originating from the moon! He assigns Commando Cody, scientist and man of action with a secret flying suit, to investigate. Soon, Cody is battling Earth thugs in the pay of Krog the moon man and making trips in his experimental rocket to the moon itself, in a perilous and all but singlehanded effort to thwart the planned invasion of Earth.

Young Pauline is left a lot of money when her wealthy uncle dies. However, her uncle's secretary has been named as her guardian until she marries, at which time she will officially take possession of her inheritance. Meanwhile, her "guardian" and his confederates constantly come up with schemes to get rid of Pauline so that he can get his hands on the money himself.

Hammond, owner of the town's stagecoach line and a leading citizen, is opposed to Idaho becoming a state, and kills Randolph Meredith, owner of the town's newspaper, for endorsing it. Meredith's sister Barbara, expert with a bullwhip and pistol, dons a black costume and mask and becomes "The Black Whip", dealing a blow to Hammond and his gang each time they perform some heinous act in their efforts to keep the town, and their power over it, unchanged. Aided by government agent Vic Gordon, Barbara confronts Hammond in a final showdown just as the town votes on whether or not to accept statehood.

Tom Wayne rescues Clancy, Renard and Schmidt in the Arabian desert and they join him in going after El Shaitan, a bad guy who is never seen as he tries to wipe out the Foreign Legion.

Corporal Larry Grant and Sergeant "Mac" McGowan, of the United States Marine Corps, are rival for the love of Frances Schiller, but team up to hunt down "The Tiger Shark," a mad, scientific wizard who is holding Sergeant William Schiller, Frances' brother, a prisoner on a wild, jungle island in the Pacific.

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?