Cowboy Larry O'Day and his sidekick Lucky Smith happen upon a distraught Barbara Hartwell, who is about to be arrested for the murder of her uncle. With Barbara behind bars, Larry is determined to find the real killer and soon finds himself in the middle of a mystery involving crazed German entomologists and a smuggling ring bringing Chinese "picture girls" across the Mexican border for sale to wealthy Chinese bachelors.
Shortly after Brand kills Gelbert, Tom Rayburn arrives on the scene and is accused of the murder. Escaping, he goes after Doc Mathews, the man that can prove his innocence. Brand is also after Mathews and intends to keep him from testifying. But Mathews is a ventriloquist and this will lead to Brand's downfall.
Harris and Rigby own a circus. Rigby is a counterfeiter and frames his partner. The Mesquiteers learn Rigby is the culprit and get a confession from one of his men only to lose the case when the man is murdered in jail. The Mesquiteers try again and send Lullaby to try and win some of the fake bills in a card game.
Kalmus is after the freight contract held by Summers. When his gang kill Summers, Tex and Duke step in to help Madge keep the freight line going. When they foil the gang's further attempts, Kalmus gets the Judge to jail the two.
Gene and Frog, out to stop a bunch of cattle rustlers, assume the identities of what they believe to be dead bandits, which soon gets them in big trouble.
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.
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.
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.
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.
Hoppy goes undercover as an outlaw (which permits him, for once, to drink and be mean to children) to track down a bunch of outlaws operating along the border. Loco, the head bad guy, deflects suspicion from himself by pretending to be a moron.
Tex and sidekick Grass join McGill's traveling show. When Price has McGill's wagons burned, Tex becomes the county tax collector to earn money. This leads to trouble as one of those owing money is Price who says he will not pay. Business doesn´t go as plan.
As the sheriff of a small western town, Autry sings his way into a relationship with Eleanor, a singer from a Chicago nightclub who earlier witnessed a murder.
The Commandant is making life rough for the colonials in Spanish California. While trying to help, Zorro is charged with the murder of the new Governor, but in the end he triumphs over the evil Commandant.