Jim Steele spots Pete Dawson taking horses over the Mexico-Texas border, but Dawson has an alibi. A new group of recruits arrives at the Ranger station, among them Tex Wyatt, the son of Ranger Captain John Wyatt, whom he hasn't seen for many years. Captain Wyatt tells Tex that he is in the Rangers strictly on his own merit and there will be no favors played. He assigns Tex to pick up Dawson's trail, but orders that no arrest be made without proof.

Jimmy finds a dying Ranger Braden who asks him to give his money belt to his sister. When he rides into town he finds another man claiming to be Ranger Braden. When the money belt is found in Jimmy's saddle bag, the fake Marshal tries to arrest him. But Jimmy escapes and hopes a telegram to Ranger headquarters will clear him.

Kate Diamond owns the Roaring Falls Trading Post from where she directs her gang's gun-smuggling to the Indians. After she short-changes smuggler Stacey, his men attempt to steal the hidden guns, and attack her foreman Nebraska, but he is saved by Jimmy and "Cannonball" on their way to file a homestead claim at Canyon City. Jimmy renews a long acquaintance with Sheriff Harris and his daughter Jessica. The sheriff is wounded by half-breed Danny when he finds a rifle hidden in the latter's wagon, but Jimmy captures the outlaw, a go-between for Kate and the Indians.Wounded and in bed, Sheriff Harris ask Jimmy not to tell Jessica that she is only adopted and that Nebraska is really her father, although he believes her to be dead.

An obscure entry in the musical Western cycle, Swing, Cowboy, Swing was produced by and starred country & western bandleader Cal Shrum. Shrum and his band, the Rhythm Rangers, are warned away from playing a theater in Big Bend by Cal's brother, Walt Shrum and his Colorado Hillbillies. Ignoring the warning, the Rhythm Rangers arrive at the theater only to be shot at by a masked stranger. With the help of stranded vaudeville performer Max "Alibi" Terhune and his dummy Elmer, Cal manages to catch the mystery shooter who turns out to be Frank Lawson (Frank Ellis). The film apparently did not generate enough interest for a series, but was re-released by Astor Pictures in 1949 under the title Bad Man From Big Bend.