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.

Veteran cowboy star Johnny Mack Brown plays a cattle buyer turned prairie sleuth in this low-budget oater from Monogram, which co-stars perennial old-timer Raymond Hatton as a retired U.S. Marshal assigned to investigate the mysterious disappearance of a rancher. As the two old friends soon learn, a gang of smugglers headed by the town's banker (Frank LaRue) needs the use of the Flying Arrow Ranch for their nefarious purposes.

After serving 5 years in prison for embezzling church funds, Dr. Ephraim Nye returns to Ostable and the scornful gossip of its residents, led by Althea Bemis. There is a typhoid epidemic, and Dr. Nye believes it to be caused by the water in a pond that Judge Copeland, the brother of Dr. Nye's dead wife, Fanny, wishes to use as the source of municipal water supply. Only Katherine Minot supports Dr. Nye, but biologists prove him correct; and Dr. Nye confronts Copeland with proof that he went to prison to protect Fanny, the actual criminal. Copeland finally consents to the marriage of his daughter, Faith, to Tom Stone, the son of his enemy; and Katherine spreads the news of her engagement to Dr. Nye through Althea.