The Big Four ruled a cattle empire. They were the men who had fought and killed to win the land from the Comanches, and now they were not about to hand it over to government squatters no matter what the consequences would be. Martin Kelso has been away for two years, and upon his return, finds that the peaceful plains he calls home have exploded in violence and murder. Cattlemen are ruthlessly driving squatters from their rightful homesteads, and the sheriff, Martin's own father,has become a useless drunk. There is no law in Rio de Oro until the sheriff's son decides to take it into his own hands. He will bring peace to Rio de Oro until the sheriff's son decides to take it into his own hands. He will bring peace to Rio do Oro or die trying.