After killing a man in self defense, Buck Duane becomes an outlaw, a companion of the gunfighters and rustlers who live along the Texas border. In a camp on the Mexican side of the river, he finds a young girl held prisoner and, in attempting to rescue her, brings down upon himself the wrath of her captors. Henceforth, he is forced to live a lonely life, hunted on one side by honest men, on the other by outlaws. Then, one day, a big-hearted captain of rangers takes Buck into his camp, wins him a pardon, and makes him a ranger, pledged to fight for the law rather than against it. The girl whom he attempted to rescue also finds good in Buck.