Nancy Evans, the proud owner of the West-East circus, is continually pestered by George Ward, the manager of the circus, to sell the ranch in Mesquite County which her grandfather left her. Nancy refuses because she does not need the money, but soon a series of mysterious accidents occur that drive the circus into bankruptcy. Nancy again refuses to sell, however, as the circus people now need the ranch as a place to live. Unknown to Nancy, Ward and his henchman Steve are scheming to buy her ranch at a low price because it is to be the site of a new state dam and thus is very valuable. Ward and Steve vow to drive Nancy off her ranch, just as the accidents they arranged have driven her circus out of business. The circus people make the journey to Mesquite, where they are rescued from a run-in with Ward's men by Stony Brooke, Tucson Smith and Lullaby Joslin, who are known as The Three Mesquiteers. Nancy and the others then settle on what they think is the W-E ranch, but is actually the 3-M ranch with the sign turned upside-down. The Mesquiteers, who know that the real W-E ranch is in terrible disrepair, haven't the heart to tell Nancy so they try to fix up the W-E ranch for her. During the Mesquiteers' first night at the W-E ranch, Ward's men, who do not know that Nancy is at the 3-M ranch, set the barn on fire, but the Mesquiteers put it out and rescue the horses. The next day, the trio inform Nancy of the mixup but offer to let her stay on until the circus gets back on its feet. They also offer to help Nancy get a permit to perform at the country fair. When Ward states that they need $1,000 for equipment, they loan the money to Nancy in exchange for the mortgage on her ranch. When Lullaby takes the deed to town to record it, however, Ward's cohort, Mike Abbott, buys it from him for $1,500. While Lullaby is gone, Nancy receives a letter from the state offering her $75,000 for her ranch. Nancy is ecstatic but when Lullaby returns and explains that he sold the mortgage and then was robbed of the money as he was riding back. Nancy believes that the Mesquiteers swindled her, so after she storms off, they go to Ward's hotel room, where they find a previous letter from the state which reveals Ward's knowledge of the dam. They try to inform Nancy, but she refuses to believe them. The Mesquiteers then realize that not only do they need to get money for her but also for themselves, or else they will not be able to meet their own mortgage payment. They steal Nancy's show horse Rajah and begin training him to be a trotter in order to enter him in an upcoming race with a prize of $2,500. Overcoming various obstacles, the Mesquiteers and Nancy, who has been won over by them, attend the race and Rajah wins. Ward's attempt to interfere with the race proves his culpability to Nancy, and after he and his gang are arrested, Nancy sells her ranch to the state. Now financially secure, the circus people thank the Mesquiteers for their help and move on to begin performing again.