A prospector discovers natural cement and suggests it should be used for a new dam. But this is the last thing the badmen of Trail End want, as they have a monopoly of the wagons needed to haul rocks to the site. A pretty sheriff notwithstanding, it's a job for a singing marshal.
Burgess and Greeley are rustling horses and shooting Indians. When they kill Manual they frame Lieutenant Allister. His older brother John now attempts to defend him at his murder trial.
One man wants to control all the land in the state to graze all his cattle. His band of outlaws are raiding ranchers and homesteaders, trying to drive them out. Rocky and Fuzzy are brought in to help stop the raiders and keep the land for the small ranchers and homesteaders.
Ben Wade and his partner Frosty return to Bellounds' ranch where twenty years earlier Wade was wanted for murder. Unrecognized, he gets a job on the ranch and soon becomes involved in Folsom's cattle rustling and a chance to settle an old score.
Chasing jewel thieves, Captain Carson and Magpie head for the border where Carson, posing as a Chinaman, opens a store that buys jewelry. To flush the thieves into the open, Carson wins all their money at poker. They agree to sell him the jewels but plan to kill him and keep both the jewels and the money.
A cowboy goes to help out his friend, who has been falsely accused of murder. The two find themselves in the rugged and mysterious Pallidi Mountains, where they come up against an outlaw gang that is searching for a buried Inca treasure, which is guarded by a lot Inca tribe.
Ken Maynard's exceptionally intelligent horse, Tarzan the Wonder Horse, is the star of this western about evil cowboy Steve Frazer (Welch) who gathers horses for slaughter, whose meat is sold to pet food manufacturers. The wild horse Tarzan frees the doomed horses from their corrals, and Frazer convinces the Sheriff that Tarzan is a threat and can be shot on sight. Local cowboy Ken Benson (Maynard) and rancher Pat Riley (Kennedy) work together to clear Tarzan's good name and put Frazier behind bars for his evil deeds.
Trouble starts when Bill Larkins and his two sons move in with his brother Joe. They start rustling cattle and then kill Rod's father with Joe's gun. The Sheriff and Rod think they did it and are after proof.
Henry Jethrow is after the Wilson ranch. He has George Wilson unknowningly sign a note for the ranch, has him killed, and then presents the note. The Pinto Kid, investigating cattle rustlers, accidentally drops his glove at the murder scene and now has a price on his head. He has Beth Wilson turn him and use the reward money to reclaim the note. Now he has to escape jail and find the real killers.
Banker Mason is after the ranchers land so he can resell it to the railroad for a profit. He has the railroad agent killed and replaces him with his stooge who then offers even less than Mason. But Rocky eventually suspects Mason and when Bill Anderson informs him the agent is a fake, they head out after Mason
Montana and sidekick Pancho hire on at the Lopez rancho to fight Daggett and his outlaw gang. But Lopez's foreman Barnes is one of Daggett's men and he frames Montana for murder.
Howell breaks up a train robbery only to find that it's a fake. However the money is missing and he is blamed. He escapes and sets out to find the real thieves. He must also avoid being caught visiting the Collins ranch to see Doris.
As war looms in the Pacific, even cowboys are called on to fight the enemy. Horses are desperately needed by U.S forces stationed in the Philippines, and the Range Busters - Crash Corrigan, Alibi Terhune, and their newest partner, Davy Sharpe - are hired to accompany a herd to the islands. But first they must battle Axis spies right in Texas, as they foil a plot to steal the very horses destined for shipment.
The notorious outlaw Black Bart has reappeared and the Range Busters are sent to investigate. When they find that Black Bart is now a respectable citizen and that someone is impersonating him, they set a trap for the robber.