As the Texan militia inside the Alamo braces for Gen. Santa Anna's attack, soldier John Stroud (Glenn Ford) is chosen to go to the nearby town of Ox Bow to warn the women and children. He arrives to the scene of a massacre, with his wife and young son among the victims, perpetrated by a gang of Texans fighting for the Mexican side and led by the outlaw Jess Wade (Victor Jory). Branded a deserter for having left the Alamo before its fall, Stroud infiltrates Wade's gang to extract his revenge.