Working undercover, Rangers Bob and Wally arrive to take up ranching. Out to stop them is Bill Nash and his men. When Bob plans to file on a ranch, Nash finds out and heads for the Registrar ahead of him.
Night riders are terrorizing homesteaders, and the town doctor tries to keep the locals from forming a vigilante group. After more towns people are killed, however, the rest of the town makes the doctor the town sheriff and tells him to clean up the gang.
A crooked real estate manipulator sells worthless land on mortgage to flood refugees, then tries to profit by reselling the land to the state, committing murder in the process, as the Three Mesquiteers work to bring him and his gang to justice.
Dan Ward, reformed and last member of an outlaw family, meets Molly Clark in a rocky draw near town. Ted Wells, a henchman for Dan's enemy Jim Swain, attempts to shoot Dan but is outdrawn and killed by the latter. Molly disappears and Dan learns that she and Wells had ridden there together. Sheriff Bob Larimer tells Dan that Molly is in love with Bert Gilmore and tried to have him ambushed. Dan takes a risky job with mine owner Pember of getting the $10,000 payroll through to the mine. Swain suspects that Dan is carrying the payroll, but his gang is unable to stop Dan. Betty Pember disregards Dan's warning that the hills are filled with Swain's men and she starts for town. She is kidnapped by Gilmore and Molly and Dan ride to her rescue.
Ace Beldon is in prison, but with his stolen bonds not recovered, Capt. Saunders has an idea. He sends Graham to prison and has him and Beldon break out. With Ranger Raymond assisting, they make their escape and get to the hangout run by Stone. But the plan starts to go awry when Sam overhears Graham talking with the Captain and reports back to Stone.
Bank employee assigned to tell Arizona rancher her property is no good gets suspicious when her foreman agrees. Turns out his banker boss and the foreman know there's silver on that property.
Cattlemen's Protective Association agent Tom Wade masquerades as outlaw Luke Bardes, hired to help Jed Travis persuade his niece Jennifer to sell him her ranch at a ridiculously low price, enabling him to turn a huge profit when the railroad has to buy the right-of-way through his property. Tom finds himself in big trouble when Bardes breaks out of jail and shows up at the ranch with a few of his rough-and-trouble companions.
Jim Waters arrives at Ed Parks' ranch to find Parks' cattle herd mysteriously increased. Hamp Harvey has been losing cattle and he suspects Parks. But the culprit is Harvey's foreman Brent who gets his orders from the town's leading citizen Sig Barstell. Barstell wants Harvey's ranch and after trying to frame Harvey by killing Parks, Waters takes over and goes after both the killer and the rustlers.
An evil deputy is using Indian half-breeds to rustle cattle. This causes trouble between the cattlemen and Indians. Hoppy, Windy and Lucky see that justice is served. Songs abound.
Stan and Ollie try to deliver the deed to a valuable gold mine to the daughter of a dead prospector. Unfortunately, the daughter's evil guardian is determined to have the gold mine for himself and his saloon-singer wife.
Not quite a western, not quite a historical drama, Under Strange Flags is a little bit of both, and a lot of former RKO Radio cowboy hero Tom Keene. The star is cast as Tom Kenyon, a roving adventurer in Mexico during the Revolution. Hoping to protect the silver mine owned by heroine Dolores De Vargas (Luana Walters), Tom receives unexpected assistance from none other than rebel leader Pancho Villa (Maurice Black).
Jeff arrives in town to see the Sheriff only to find him just killed. The culprit is Clay Wheeler. When Jeff becomes friendly with Letty, Clay sends his man Ortega to kill him. Jeff foils the attempt and gets him to confess that Clay was the killer. With only old-timers Lafe and Bill to help, Jeff heads after Clay and his gang.
When he swaps horses with the Tombstone Kid — a wrongly accused man on the run from the law — singing cowboy Tex Randall gets arrested by the local sheriff in a case of mistaken identity.
The fourth of 12 singing Westerns starring the "Silvery-Voiced Baritone," Fred Scott, Melody of the Plains begins peacefully enough with Scott, as cowboy Steve Condon, warbling Don Swander and June Hershey's "Albuquerque." The story quickly takes a rather grim turn when one of Steve's colleagues is shot and killed after selling out to a gang of rustlers. Mistakenly believing he fired the deadly shot, a dejected Steve, along with sidekick Fuzzy, goes to work for Bud's father, a rancher nearly forced into bankruptcy by a crooked land developer.
There is a range war between the ranchers led by Tilden and the outlaw gang of Link Carson. Wanted outlaw Dude Ramsey arrives and joins up with Tilden. First he saves the ranchers from Carson's trap and then exposes Pearson as Carson's informant and killer of Steve Warner.