The Great Secret

Mota is a Martian representative, who has come to impose interplanetary law on the Earth (which has become too dangerous); opposing his authority is Kent Fowler, who resists the alien plot, without understanding its details.

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.

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

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.

Jerry Blake (aka Federal Operator 99) teams-up with Joyce Kingston to thwart the plans of escaped crime boss Jim Belmont.

An expedition arrives on an uncharted jungle island to rescue the local natives, led by a jungle boy, from a volcano that is about to erupt.

Escaped Prisoner 39013 impersonates the rich and influential Horace Granville, allowing him to create a variety of disasters. Fortunately, he is thwarted repeatedly by three daring circus daredevils.

Disaster seems imminent when scientists discover that the planet Mongo is about to crash into Earth. Luckily, heroic young Flash Gordon is on hand to lead an investigative mission into outer space and onto the speedily approaching planet. There, he and his best girl, Dale, who is along for the ride, learn that Ming, the devious ruler of Mongo, has purposely put the planet on a collision course with Earth, and only Flash can stop him.

Dusty Bates observes some smuggled jewels hidden in a crate aboard a ship; he is pursued by low-lifes when the crate is put ashore.

The nefarious Dr. Fu Manchu searches for the keys to the tomb of Genghis Khan, in order to fulfill a prophecy that will enable him to conquer the world. His nemesi, Dr. Nayland Smith and his associates fight to keep the evil doctor from getting his hands on the keys. In 1943 the serial was edited together into a feature movie also called Drums of Fu Manchu.

The obsessive scientist Dr. Miller is working on a matter-transmitter invention called the Paratron; a conspiratorial team of spies and no-goods pursue him to Alaska, trying to steal the device.

Two British officers are assigned to collect information to convict Captain Kidd of piracy.

Ruby Blackwell, typical young girl of Arizona, lives with her brother Tom, and their widowed mother in a cabin in the mountains. One day Tom takes Ruby on a lion hunt. They track a puma, or mountain lion. Tom shoots the beast, which, wounded, bounds into the canyon. Tom instructs Ruby to proceed to the ridge and await him there, while he follows the puma up the mountainside. Ruby discovers the cubs belonging to the puma which Tom has shot, and she immediately becomes so engrossed in playing with the huge kittens that she forgets the rendezvous her brother had appointed. Tom finally locates her. The cubs are taken home. They grow up around Ruby like friendly dogs. Pete Lopez, a bad Mexican, who admires Ruby very much, tries to steal one of them at night, after Ruby has refused to sell the animal to him, and the baby puma defends itself vigorously until Tom and Ruby rush to its rescue...

Government agents try to thwart smugglers, while some sort of plot unfolds, about a hidden treasure revealed by cursed coins.

Kit Cardigan seeks the killer of his father...among other plot threads leading up to the famous historical incident.

Mystery and adventure, surrounding a stolen rubber harvest.

Jim Dorn endeavors to protect Jean McNain from a man she knows has committed a murder, Carter Snowden

Four flying G-Men protect America against enemy spies; one of the four assumes the identity of The Black Falcon, to befuddle the saboteurs even further.

Pulp hero "The Spider" seeks to destroy all criminals. In this serialized adventure, he battles The Octopus, who intends to replace the government of the United States.

Mandrake and his team attempt to prevent "The Wasp" from stealing and using a new Radium invention.