From his secret laboratory, Captain Z-Ro and his associates use their time machine, the ZX-99, to learn from the past and plan for the future.

Two prospectors, one the father of Skye "Lightning" Bryce and the other the father of Kate Arnold, find a large gold deposit belonging to an Indian tribe. They head for home but each sends a note to their respective off-springs advising them of their good fortune. One of the fathers conceives a plan of taking a dagger and wrapping a piece of string around the blade, after which he prints on the string with a lead pencil, the exact location of their find. If something happens to them, the string goes to the son and the knife to the daughter. That night an Indian approaches their camp and blows some mysterious wolf powder which causes a man to see wolves in place of human beings. Lightning's father see his partner as a wolf and stabs him to death; later he is brought into town in a dying condition but before dying, hands the knife and the string over to the sheriff with instructions to deliver to Lightning and Kate.

When some men are attacked by Indians, a survivor obtains an Indian medicine arrow. An Indian tells Blade he has found gold but will not tell him where until he has that arrow. So Blade starts killing the survivors of the attack but fails to get the arrow. One of the men he kills is John Cardigan and Kit Cardigan, a Scout for Custer, now starts looking for the killer of his father.

An expedition sets off for the last land of Mu, where legend has it that a killer death ray is emitted from the eye of a golden idol.

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.

Rex, a wild stallion, and Rinty, a police dog, are pals. Their master , John Sheldon, is framed for murder, and Alice Ingram plans to race Rex for money to pay for John's legal defense. Meantime, Frank Nolan, who has falsely accused John, sets out to steal Rex for himself.

An intrepid reporter and his loyal friend battle a bizarre secret society of criminals known as The Vampires.

Superhero Captain America battles the evil forces of the archvillain called The Scarab, who poisons his enemies and steals a secret device capable of destroying buildings by sound vibrations.

The misadventures of a suburban boy, family and friends.

Crash Corrigan, a recent graduate of Annapolis, and Diana, a go-getting reporter, join Professor Norton for a search for the source of a string of earthquakes, Atlantis. They ride Prof. Norton's rocket submarine searching the sea and little Billy Norton, the professor's son stows away, of course. When they find Atlantis they are caught in a war between peaceful Atlanteans, note their white capes, and war-monging Atlanteans, note their black capes. After many harrowing moments for Crash, Diana, Prof. Norton and Billy, they barely get away with their lives when they escape a tower of Atlantis raised to the surface for the sole purpose of dominating or destroying the Earth (Which one depends on the compliance of the upper world dwellers.)

Police detectives battle the League of Murdered Men, a gang of resurrected dead criminals.

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.