After his partner is killed, aging Texas Ranger Jake Cutter (John Wayne) is assigned to capture gambler Paul Regret (Stuart Whitman), a condemned prisoner who managed to escape hanging, and return him to Louisiana to face his sentence. But once Cutter has him in custody, they encounter the Comancheros, a fierce band of outlaws providing guns and booze to the Comanches, and are forced to work together to stop them. When Regret proves his worth in the fight, Cutter begins to reevaluate his duties.