During a U.S. Cavalry patrol mission to Ft. Bowie, Lt. Jonathan Davenport, the newly appointed West Point-trained commander of the troop, clashes with his second-in-command, Sgt. Wade McCoy, a seasoned veteran of the "tomahawk trail." Davenport, ignorant of the ways of the West, cloaks his weakness with a mask of arrogance and contempt. Due to Davenport's misjudgment, the platoon loses its ammunition and supply wagons during an attack by the Apache Indians. That night, the Indians return and steal the troop's horses, forcing the men to proceed on foot through the desert to Ft. Bowie.
The men resent Davenport's incompetence and his condescending attitude, and tensions mount when Davenport accuses McCoy of cowardice because of his constant criticisms.
Suffering from sunstroke, Davenport then collapses. Aroused by the sound of rifle fire in the distance, signaling that Fort Bowie is under attack, Davenport orders his men to shoot on sight, despite McCoy's protests.
Continuing on, the troop is drawn into a skirmish with a band of Indians, and after driving off the braves, they capture two young women. One is Ellen Carter, the daughter of the commander of Fort Defiance, who was taken prisoner by the Indians after a massacre at the fort. The other is Tula, the daughter of Victorio, the chief of the Apaches.
When Davenport, raving from the heat, accuses Ellen of being an Apache squaw and orders both women bound, McCoy rebels and assumes command. That night, Pvt. Barrow, one of the enlistees, attacks Tula, and the sergeant comes to her aid, thus earning Barrow's emnity. Throughout the assault, Tula remains silent, having promised McCoy that she would not cry out and alert the Indians. On the trek back to the fort, Davenport begins to regain his equilibrium, causing McCoy to fear a court-martial, but McCoy's friend, Pvt. Reynolds, assures him that he has done the right thing. Upon reaching Ft. Bowie, the patrol discovers that the garrison has been massacred. Davenport, raving once again, addresses the dead commander and then collapses, and Miller, his orderly, blames McCoy for his superior's condition. After first issuing orders to continue to Fort Benson, McCoy decides to stay and secure the fort.
That night, as Apache drums drone in the distance, Barrow assaults Ellen and she kills him while protecting herself. Later, Ellen confides to Tula that she has fallen in love with McCoy and implores her to plead with her father to end the warfare. Soon after, a band of Indians attack and fell Davenport with an arrow. After McCoy and his men drive off the first wave of Indians, Johnny Dogwood, the troop's scout, listens to the drums and warns that the braves have told Victorio that Tula has defected to the white man. Tula decides to risk her life to meet with her father. As soon as she climbs the fort wall, she is captured by two braves, who take her to Victorio. After hugging his daughter, Victorio calls off the attack and the Indians ride away. Miller then promises to support McCoy at the inquiry, and Ellen and McCoy embrace in relief.
