Saddlemates

When Congress changes a boundary between Mexico and Texas, the rangers of the Red River headquarters leave their station, and a U.S. Cavalry unit, headed by Colonel Langley, takes over and prepares to deal with the hostile Indians. Ranger Captain Miller warns Langley that the warmongering Wanechee will be difficult to apprehend, and that his own best men, "Stony" Brooke, "Tucson" Smith and "Lullaby" Joslin, who are known as "The Three Mesquiteers," are searching for him. When the Mesquiteers return to the post, they learn that Langley wants them to stay on as scouts. The Mesquiteers want nothing to do with the cavalry, but change their minds after meeting Langley's pretty daughter Susan. After they sign on, the Mesquiteers tell Langley that he is wrong to initiate peace talks with the Indians, but he insists that the fighting must end. He sends Stony, Tucson and two troopers to follow the post's half-breed interpretor, LeRoque, on a mission to propose a peaceful meeting with Wanechee and the other chiefs. LeRoque, who is actually Wanechee, plans an ambush, but Tucson spots the trap. Although Tucson and Stony escape, one of the troopers is killed, and Langley, thinking that the Mesquiteers are to blame, arrests them. Susan, who believes that they should be given another chance, talks Langley into releasing them, but after they are involved in a saloon brawl, Stony is discharged from the cavalry and Susan turns against him. Determined to investigate LeRoque, of whom they have become suspicious, Tucson and Lullaby also get discharged. While exploring the hills, the Mesquiteers are captured by Wanechee, whom they do not recognize as LeRoque, while he is preparing a trap for a wagon train. The Mesquiteers escape with two Indians as prisoners, and while they question them at their hideout, LeRoque tells Langley that there will be no peace while the Mesquiteers keep their prisoners. Langley sends Lieutenant Bob Manning to get the Mesquiteers, but while they are talking to the troopers, LeRoque's henchman beats the prisoners to death to prevent them from talking. After the Mesquiteers are arrested for murder, LeRoque convinces peaceful Chief Thunder Bird that the Indians must attack the wagon train, which carries rifles as well as Langley's wife and son. As Manning is returning the Mesquiteers to the post, LeRoque sends word to Langley that the wagon train has been delayed until the next day, and that he should meet the chiefs for a peace treaty. Langley and his men are captured by LeRoque, and after the Indians put on their uniforms, they meet the wagon train. Meanwhile, the Mesquiteers reach the post, and Susan pleads with Bob to let them go. He refuses, but the Mesquiteers escape from the guardhouse, and while Lullaby and Stony ride to find the colonel, Tucson goes to aid the wagon train. Stony and Lullaby arrive with Langley as the settlers are about to be overwhelmed, and soon LeRoque is exposed as Wanechee. Later, the Langleys express their thanks to the Mesquiteers, who then leave to begin peace talks with Thunder Bird.