In the rugged Oregon Cascade country of 1871, the U.S. Cavalry searches for the elusive Black Eagle, a Shoshoni warrior who has inflamed the otherwise peaceful local Indians to make frequent attacks on the fort. Determined to subdue Black Eagle, Lieut. Niles Ord, who has spent his life among tribal peoples, raids a ceremonial village, but instead of capturing the rebellious brave, he takes a more willing prisoner: Little Deer, who had been captured from another tribe to be Black Eagle's bride. Upon returning to the fort, Niles meets his new commander, Maj. Roland Dane, an arrogant man who mistakenly assumes that the Shoshoni are similar to the Plains Indians he fought in the Midwest. Dane, insanely jealous of even the smallest attentions shown his pretty but flirtatious wife Sylvia, is already suspicious of Niles, who had a brief romance with Sylvia two years before she met her husband. Bored and resentful at having been brought to a frontier outpost, Sylvia begs Niles to run away with her. Meanwhile, Little Deer tries to convince Niles that she is the woman destined to be his wife. Niles is amused by these attentions, but he is worried about Capt. Boyson, the former commander of the fort, who, because he lapsed into alcoholism after suffering torture at the hands of the Indians, faces a court-martial. Determined to be rid of Boyson, Dane sends him to another fort to face charges, accompanied by only a few soldiers. Soon afterward, Black Eagle returns Boyson, his belly slit open, to Dane's fort on horseback. Niles and his Indian scout Nato try to convince Dane that Black Eagle wants to lure small groups of soldiers from the fort, thereby gradually depleting it of manpower. Dane scoffs at these assertions, however, and orders a detail to find the braves who killed Boyson. Leading the patrol himself, Dane is unaware that the men are being led into a trap. When Black Eagle attacks, all but Dane and one other soldier are killed. Back at the fort, Dane sends Nato to Fort Rock to request reinforcements, but the scout returns with distressing orders: Dane must send troops to Fort Rock to help battle the Modocs. Realizing that few men are left to protect the fort, Niles decides that he must find and kill Black Eagle, who, the drums say, is in a holy place preparing himself for the big attack on the fort. Because Little Deer knows the location of the holy site, she volunteers to lead Niles to the spot, and Niles, impressed with her bravery, finally accepts her love. Niles and Little Deer find Black Eagle, but the warrior escapes. Shortly afterward, Sylvia is captured while taking her daily ride outside the fort. Dane tracks the raiding party to Black Eagle's camp, where, rather than see his wife touched by Indians, he shoots her. They, in turn, kill him, and then ride out to launch the big attack. Back at the fort, the remaining soldiers prepare for the approaching war party by hiding in the cemetery outside the gates, a strategy designed by Niles. As the attacking braves draw near, the troopers surprise them with gunfire, throwing them into complete disarray. Niles pursues Black Eagle and the two men engage in a knife fight. Niles pins Black Eagle to the ground, finally suffocating him in the dirt. As the cavalry returns to the fort, Little Deer runs out to greet her beloved Niles.