During his first patrol, Maj. Wharton, an arrogant political appointee, slaughters a band of Apaches even though they are about to surrender. Watching in dismay, Capt. "Tomahawk" Thompson, named for the weapon he always carries, fears that Wharton's policy of annihilation will foment an Indian war. Upon returning to Fort Bowie, Wharton reports to his commanding officer, Col. Jim Garrett, who disagrees with Wharton's policies, but is unable to countermand him. When word comes that Victorio, the Apache leader, is rallying his braves, Garrett sends Thompson to escort the colonel's wife Allison back to the safety of the fort. That night, before he leaves, Chenzana, Victorio's spurned consort who works as a laundress at the fort, warns Thompson that Victorio is bent on revenge. Later, in Tucson, the glamorous Allison refuses to return to the fort with Thompson, so he tosses her into the back of a wagon. On the journey back to the fort, Allison makes romantic advances to Thompson, but he rejects her. After fending off an Indian attack, Thompson and Allison finally reach the fort. Disgusted by life on the frontier, Allison chastises her husband for not sacrificing his ideals to advance his political career. Then, to wound Garrett, Allison lies that Thompson made love to her. The next day, Garrett sends Wharton and his troops into the field to attack the Indians, assigning Thompson the suicidal task of convincing Victorio to surrender. As Thompson is about to depart on his mission with Sgt. Kukus, Allison warns him that her husband is trying to kill him, and Thompson assures her that Garrett's motives are purely tactical. Before leaving, Thompson requests the colonel to issue explicit orders to Wharton to hold back his troops until Thompson and Kukus are clear of the area. After Wharton and Thompson depart, Allison confesses to her husband that she lied about her affair and he contemptuously informs her that Thompson's death will be on her conscience. Meanwhile, led by Chenzana, Kukus and Thompson meet with Victorio, who refuses to surrender. Spotting Wharton's troops snaking up the mountainside, Victorio takes Kukus and Thompson prisoner and then slaughters Wharton and his men. After ordering Thompson and Kukus to be left behind and tortured, Victorio rallies his braves and heads for the fort. Chenzana frees the captives and Thompson sends Kukus for reinforcements while he rides back to the fort. Just as Garrett is notified that he has been relieved of his command, the Apaches storm the fort. The Indians scale the walls, but Garrett, the women, and a handful of surviving troopers retreat to the mess hall. As Garrett fires at the marauders, Allison reloads his weapons and they reconcile. Just when all seems lost, Thompson charges the fort with his reinforcements. Victorio is about to bludgeon Allison when Thompson bursts into the room and fights him off with his tomahawk. As Thompson and Victorio grapple, Garrett fells the Apache with a bullet. After the colonel apologizes to Thompson for misjudging him, Thompson and Chenzana embrace.