Supernatural events on the range prompt an investigation by cowboy Brown in this western.

At the height of the frontier era, a train races through the Rocky Mountains on a classified mission to a remote army post. But one by one the passengers are being murdered, and their only hope is the mysterious John Deakin, who's being transported to face trial for murder.

Stodge City is in the grip of the Rumpo Kid and his gang. Mistaken identity again takes a hand as a 'sanitary engineer' named Marshal P. Knutt is mistaken for a law marshal. Being the conscientious sort, Marshal tries to help the town get rid of Rumpo, and a showdown is inevitable. Marshal has two aids—revenge-seeking Annie Oakley and his sanitary expertise.

In 1890s Seattle, a deputy marshal and his female partner set out to bust up a ring that kidnaps teenage girls and sells them into prostitution.

Will Kane, the sheriff of a small town in New Mexico, learns a notorious outlaw he put in jail has been freed, and will be arriving on the noon train. Knowing the outlaw and his gang are coming to kill him, Kane is determined to stand his ground, so he attempts to gather a posse from among the local townspeople.

Mountie Matt O'Brien is assigned to escort Miss Owens to a remote outpost. But when he finds an illegal mining operation there that is smuggling gold across the border, his superior Sgt. Means orders him to leave.

Bantam-weight western star Don "Red" Barry certainly deserved his designation as "The Cowboy Cagney" in Republic's Desert Bandit. Barry is cast as two-fisted Texas Ranger Bob Crandall, who after being dishonorably discharged heads to the Mexican border to start life anew. He falls in with a gang of gun runners, headed by corrupt lawman Largo (William Haade). It turns out, of course, that Crandall's "disgrace" was merely a ruse to allow him to work undercover in bringing Largo and his minions to justice.

A US marshal goes undercover to bust up a bunch of rustlers.

A ranch owner turns his place into a home for boys who have lost their fathers in World War II. His evil female lawyer covets the ranch and uses a gang of local toughs, a pack of killer dogs, and a phoney rancher's beneficiary to get it. U.S. Marshal Rogers opens an investigation when the rancher is killed.

Curley Smith, a lieutenant of the Texas Rangers, gets chased by a band of smugglers after getting caught spying on them and becomes injured. Anita, the daughter of the chief smuggler tends to him and the two of them fall in love. Dean, a member of the renegade, becomes jealous of their romance, and will do whatever he can to get rid of Curley - fair or foul.

Chip of the Flying U was Johnny Mack Brown's first western entry for 1940. Brown essays the title role of Chip Bennett, foreman of the Flying U ranch. Before the second reel has tumbled over the spools, Chip finds himself falsely accused of robbery and murder. The actual miscreants are in the employ of a band of foreign gunrunners, who speak in heavily Teutonic accents. Rest assured that Chip makes short work of these bush-league Storm Troopers before the sun sets in the West. Musical interludes are provided by a group calling themselves the Texas Rangers, even though they actually hailed from Kansas City.

When Sheriff Jake sees a man at the safe and then finds the payroll gone, he trails him. Just as he is about to arrest him, the man saves his life. Still suspicious, he joins up with the man and later they learn that Melgrove, the towns leading citizen, is trying to take over the area's ranches by having his gang stop all incoming supply wagons. With the ranchers about to sell to Melgrove, the two newcomers say they will bring in provisions.