A black sergeant is forced to take command when his lieutenant is killed during the Korean War.

In October 1950, shortly after U.S. forces invade Korea, an advance Marine unit is sent to find and hold a farmhouse that is situated in a strategic mountain pass. As the Marines make their way down a snow-covered mountainside, they are attacked by waiting Chinese troops. Just before he dies, Lt. Earl D. Toland orders Sgt. Eddie Towler, the unit's only black man, to take charge of the few surviving Marines, even though Towler suggests that Sgt. Kincaid, a veteran who has been with the outfit for eleven years, is better prepared to direct the unit. Towler guides the men across the slippery, heavily mined slopes, and during the trek, Kincaid rescues one of the men when he slips and lands among the mines. As they reach the farmhouse, one of the men panics and throws a grenade inside the courtyard walls, seriously injuring a Korean woman who lives there with her part-French daughter and grandson. Once inside, the men begin to worry that the numerous Chinese troops in the area will kill them all before the advancing Marine battalion can reach them, but Towler orders the men to hold their position at all costs. Bracken, a Southern bigot, claims that black men are unsuited to be leaders. Kincaid, who thinks the men should be moved even though it would mean losing the pass to the enemy and thereby endangering their entire battalion, suggests that Towler wants to remain in the farmhouse merely to prove himself. Determined to carry out Toland's commands, Towler claims that he will kill any man who refuses to act like a Marine and defend the farmhouse. That night, as Towler contemplates their difficult situation, the men reminisce about home. A recent immigrant from Sweden named Torgil, who wants to become a citizen and bring his family to the U.S., sings a song from his native land. Crane, a cynical corporal, tells amusingly irreverent stories about high-ranking officers, and a young soldier named Cotton sings and accompanies himself on a Korean stringed instrument. Before long, an enemy patrol unit advances on the house and the shooting begins. The Marines repulse these troops, and Hunter, a Navajo from Arizona nicknamed "The Chief," volunteers to scout the area for other enemy soldiers. The Chinese capture Hunter and accompany him back to the farmhouse. To save his unit, Hunter refrains from giving the password and dies with his Chinese captors when Towler and Kincaid fire on the intruders. After Hunter's burial, the Eurasian woman living in the house thanks Towler for helping her, telling him that one day, his color will make no difference to the others. Bracken gets drunk and attacks the woman, whereupon Towler fights him and, after enduring Bracken's racist insults and epithets, threatens to kill him if he touches the woman again. After another battle with Chinese troops that costs the life of one of the men, Towler and Kincaid come to blows, but their fight is interrupted by the sound of an approaching tank. Towler and Kincaid sneak onto the tank and set it ablaze, but Kincaid's leg is crushed as he tries to get out of the way, and it must be amputated by the medic, who is unsure of his ability. Encouraged by Towler, the medic continues with the operation, and Towler donates his own blood to keep Kincaid alive despite Bracken's objections. As a line of Chinese tanks approaches, Towler orders the Marines to safer ground and protects Kincaid during an explosion, then carries him out of the farmhouse. The enemy is about to reach the two men when U.S. planes appear overhead and blast the Chinese troops. Greatly relieved, Towler and Kincaid wish each other a merry Christmas.