An American named Martin Brady, living in Mexico, works as a hired gun for a powerful family, the Castro brothers. After being sent on a dangerous mission to Texas to procure firearms, Brady accidentally breaks his leg in an unfortunate horse accident, stranding him in a U.S. border town. As he recovers, he reluctantly becomes entangled with various local figures, including an ambitious army major named Stark Colton and the major's wife, Helen. Brady is torn between his loyalty to the Castros and the possibility of a new life in the United States, further complicated by the racism and prejudice he faces due to his association with Mexico.

As Brady grapples with his identity and loyalties, conflicts arise that test his resolve both personally and professionally. Old enemies resurface, and allegiances shift unpredictably, placing him in increasingly precarious situations. He must navigate a treacherous path, balancing his complicated past with the promise of a different future.