In 1937 the life in out West has not changed much. The boys are working at the Wyoming ranch of Captain Marvin herding horses which he sells to Kurt Redman. Marvin will not sell any horses to any army, but the boys find out that Redman is a German agent shipping the horses directly to the Third Reich. When Marvin tries to stop Redman, his son Tad, who is studying medicine in Germany, is arrested and held hostage. Marvin must fire the boys as the sneaky German agents take over the ranch, but the boys will not give up their attempt to stop them.
The Mesquiteers capture a horse thief who escapes justice through a crooked judge. They gather signatures urging the governor to investigate but a friend with the petition is murdered. Stony is accused.
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.
The Three Mesquiteers convince a group of settlers to exchange their present property for some which, unbeknownst to our goodguys, is going to be worthless. They are captured before they can warn the ranchers.
Unable to legally capture and sell a herd of protected wild horses, corrupt rancher Rance Macgowan uses his trained killer horse, Volcano, to substitute for the real leader of the herd and cause havoc and death among the ranches. With the government about to drop the restrictions on rounding up the herd, the Three Mesquiteers find themselves in the middle of the controversy after their friend, Sheriff Miller is killed by Volcano.
When Professor Marsh disappears while searching for the lost city of Lukachukai, his daughter enlists the help of the Three Mesquiteers.
David Ross organizes the ranchers into a vigilante group to rid the town of outlaws. The plan succeeds but the trouble starts when some of the men form a new vigilante group and posing as the original one plunder for loot.
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.
Stony's brother George has been accused of murder and the Mesquiteers have returned to prove his innocence. But they find that Harvey rules the town along with his stooge Sheriff Gray and that George won't get a fair trial.
Cowboys from Texas is a 1939 American Western "Three Mesquiteers" B-movie directed by George Sherman.Texas has opened up land for homesteaders. Clay Allison wants their land and has his men led by Plummer try to start a range war between them and the ranchers. With each side suspecting the other of their problems, the Mesquiteers realize someone else is responsible. Stony suspects Plummer and fakes leaving the Mesquiteers to join Plummer's gang hoping to find out who it is.
After a payroll robbery the Mesquiteers catch up with the gang. But the members escape, the gang leader is killed, and they end up with only the leaders young son who is quickly sent to a work farm. They adopt the boy hoping to learn where the money is. Just as their kindness is about to pay off a gang member takes the boy away forcing him to retrieve the money. - Written by Maurice VanAuken
Commissioner Tredwell is the law of the land and he gets whatever he wants with the help of hired guns and lackey lawyer Conners. The only one who publicly stands up to Tredwell is Beecham of the Clarion. Beecham has his paper burned to the ground and when he starts a petition to make Wyoming a state, taking the power away from Tredwell, he is killed. But when Kansas Kate comes in to visit her son Conners, she sees what is going on and she takes over the paper and keeps the pressure on Tredwill. With this Conners has mixed emotions, but the boys do everything they can to protect Kate and the paper. Written by Tony Fontana
It's "The Three Mesquiteers" again. Gaucho escapes from Braden's gang only to be shot by them. The Mesquiteers drive away the outlaws and take his money on to his mother. But Isabella thinks Tucson is her long lost son and they don't have the heart to tell her he is dead.
The Cherokee Strip is off limits to the Rangers, so that is where badman Lemar operates from. When the Rangers capture his brother and the jury sentences him to hang, Lemar starts killing the jurists. Then the scoundrels kidnap the Captain's daughter Doris... Written by Tony Fontana
A champion rodeo rider returns home to track down a legendary wild horse called "Cyclone."
Stony Brooke, Rusty Joslin and Rico, the Three Mesquiteers, are returning from Mexico and are stopped at the border by Army officials, who are attempting to apprehend smugglers who are buying cheap silver in Mexico and smuggling it into the States, where they can take advantage of a silver stabilizing measure and sell it at a high price.
It is 1853 and settlers are pouring into California which means trouble for the old Spanish landowners. The El Dorado Mine Co. wants the land of Don Ortega for the minerals and is using the settlers and his friend Don Carlos to take the land over. But Tucson is on the side of Roberto and see's that something is not right with all the trouble they have been having. But the situation turns ugly for Don Ortega when Roberto is set up for a murder he did not commit.
A banker struggles to keep his bank solvent and his town from going bankrupt after the bank is robbed and all its money taken. The Three Mesquiteers ride into town and set out to help.
The Three Mesquiteers, as army scouts, soothe hostilities between the Army and Indians after both have been riled by someone with a hidden agenda - a renegade chief, who is found to be masquerading as an Army interpreter.
The Mesquiteers try to help their friend build a telegraph system, despite a local newspaper editor's attempts to sabotage the lines.