"Kansas" Tim Mason, a tenderfoot undercover agent from the East, is sent to the rough and tumble frontier town of Peaceful Valley to investigate the murder of a newspaper reporter. Kansas arrives to find Sheriff Korley and his deputies embroiled in a saloon brawl with the cowpuncher Swanee and his valet Meadows. When the lawmen rush the saloon, Kansas sides with Swanee and Meadows, and the brawl is finally stopped by the appearance of John Thornton, the cowpunchers' boss and Mark Dawson, the head of the Cattlemen's Protective Association. Swanee and Meadows convince Thornton to hire Kansas as well as Bolo, a Cossack cowboy, as cowhands, and they all ride back to the ranch where Kansas meets Thornton's seventeen year old daughter Barbara, who promptly falls in love with him. After Kansas learns that ranchers who have refused to join the protective association are being victimized by rustlers, he becomes suspicious of Dawson and searches his office, where he finds a ledger proving that Dawson has appropriated funds from the cattlemen. When Dawson surprises him in his office, Kansas escapes with the ledger, and Dawson demands his arrest. Jailed for robbery, Kansas is rescued by Bolo, Meadows and Swanee, who know that he is a federal marshal. After his escape, Kansas surmises that Dawson and his men plan to rob the stage of the 20,000 dollars raised by the cattlemen to pay for new grazing land, and with the help of his three friends, Kansas reclaims the strongbox from Dawson's men. Dawson then accuses Kansas of robbing the stage himself and demands his arrest. Intending to abscond with the cattlemen's funds, Dawson leaves for town just as Meadows, Bolo and Swanee appear to testify that Kansas is a marshal and to produce the ledger proving Dawson's guilt. The four then ride into town to confront Dawson and his men at the saloon. Startled by the sound of gunshots, Kansas' horse gallops into the saloon and begins to buck, thus diverting Dawson and his men long enough for Meadows, Bolo and Swanee to enter and apprehend the outlaws. With Dawson's arrest, Kansas settles down to marital bliss with Barbara, while Swanee and Meadows venture to Kansas City to become gentlemen.