During the latter stages of the Civil War, a gang of supposed Confederates, headed by Alex Morel (Lionel Atwill), raid all gold shipments destined for Washington from Oro Grande, California. In the first chapter, "Murder By Accident", Captain Steve Clark (Dennis Moore), is recognized as a Union Secret Service agent by Morel's accomplice Trina Dessard (Virginia Christine), and, with his friend Idaho Jones (Joe Sawyer), is ambushed in the baggage car and sent to almost certain death when the car is un-coupled and plunges down the mountainside. Leaping to safety, in order to be around for the next 12 chapters, Idaho and Steve report to Colonel Sewell (Addison Richards) in Oro Grande, and Idaho introduces himself as a Wells Fargo detective to Cathy Haines (Wanda McKay), the Oro Grande company agent. Steve and Idaho learn that the Morel raiders are only posing as Confederates, and their headquarters are at Morel's "Golden Eagle" saloon. In a raid on the hideout, Steve's brother Jim (Gene Garrick) is killed by the gang. The next victim is Confederate Army Captain Clay Randolph (Regis Toomey) who has discovered that Morel is connected with a group of Prussian spies and gives Steve a clue before he dies. The clue leads Steve to a San Francisco dive owned by Abel Rackerby (Charles Wagenheim), who, thinking he has Steve in his power, exposes the ring's activities and operation methods. Aided by the San Francisco Secret Service, Steve escapes and returns to Oro Grande, where in Chapter 13, "Golden Vengeance", he and Idaho round up the spies.

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.

A masked hero called "The Eagle" leads California ranchers in a struggle against Russian Cossacks who are plotting to take over California and turn it into a Russian colony.

Professor Davidson and his niece Diana Palmer search Africa for the Lost City of Zoloz, reputed to be the source of a large hidden treasure. Also searching is a local crook, Singapore Smith, and Dr. Max Bremmer, who plans to destroy the peace in which the native tribes have been living. However, Godfrey Prescott, otherwise known as the Phantom, is feared and respected by the natives and is able to circumvent the traps and schemes of the villains.

In 1865, Captain Mark Smith of the Confederate Army leads a band of deserters to conquer Texas and rule it as a dictator. In one of his first actions, he captures and assumes the identity of Texas' new Finance Commissioner, Colonel Marcus Jeffries, after having the real man murdered. When a contingent of Texas Rangers enters the territory, Snead, one of Smith's men, leads them into an ambush by Smith's "troopers". The Rangers are apparently wiped out, although one injured survivor is left. The survivor, nursed back to health by Tonto, swears to avenge the massacre and defeat "Colonel Jeffries" and his men.

The Black Magic cult of Ubasti, based on the isle of Lemuria, believes that Nadji, a princess of Egypt, is a reincarnation of their long-dead goddess, Ossana, and intend to sacrifice Nadji so that Ossana may be resurrected. Nadji has taken refuge at the California home of Frank Chandler, an American raised in the east and possessed of White Magical powers, who calls himself "Chandu". Vindhyan, high priest of the cult's California outpost, learns of this and ultimately succeeds in placing her in a trance which Chandu cannot easily break, propelling him to move her to safety, choosing the port of Suva in the South Seas. There, aided by his sister Dorothy, nephew Bob and niece Betty, Chandu is able to revive her and deal with Vindhyan, only to have the evil Voice of Ubasti, highest of the high priests, spirit her to Lemuria through the magic Circle of Ola. Chandu, Dorothy, Bob and Betty set out in pursuit but end up shipwrecked on Lemuria itself, with his family also now held for sacrifice while Chandu is plunged into the endless maze of caverns beneath the evil Temple of Ubasti, shrouded from his own powers by the full forces of Black Magic.

When the ancient continent of Mu sank beneath the ocean, some of its inhabitant survived in caverns beneath the sea. Cowboy singer Gene Autry stumbles upon the civilization, now buried beneath his own Radio Ranch. The Muranians have developed technology and weaponry such as television and ray guns. Their rich supply of radium draws unscrupulous speculators from the surface. The peaceful civilization of the Muranians is corrupted by the greed from above, and it becomes Autry's task to prevent all-out war, ideally without disrupting his regular radio show.

Texas Ranger tries to stop takeover of Indian lands.

A wealthy publisher uses a disguise and calls himself the Green Hornet to fight crime in his city.

A 12 episode serial starring Rex, the King of the Wild Horses and Rin-Tin-Tin, Jr. Rex is brought from the island of Sujan, where he is worshiped as a God-Horse, to the U.S. to be trained as a polo pony. He escapes, meets Rinty and with the help of Frank Bradley is returned to Sujan. The natives have been persuaded to turn against their God-Horse, however he is rescued just in time before he is burned as a sacrifice.

After Tarzan's estate is destroyed by Arabs Jane is sold into slavery by a man posing as a friendly scientist. Tarzan develops amnesia after a blow to the head. When he recovers his memory (from a later blow) he defeats the villain, recovers the fabulous jewels of Opar, and rescues Jane.

A newspaper publisher and his Korean servant fight crime as vigilantes who pose as a notorious masked gangster and his aide.

Cowboys and a businessman compete to find lost treasure.  

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.