When a lieutenant is mortally wounded in a winter ambush that decimates his platoon, he passes command to the highest ranking survivor, Sergeant Towler (Sidney Poitier). However, with the exception of African-American Towler, all of the men left alive are white. Towler feels Private Kincaid (Alan Ladd), an ex-sergeant with eleven years experience (demoted for doing things his way), is better suited for command, but the lieutenant orders him to take charge and complete their vital mission: to take and hold a farmhouse strategically positioned in a mountain pass for the advance of their battalion. After the lieutenant dies, Southerner Private Bracken (Paul Richards) initially refuses to take orders from Towler, but Towler forces him, at gunpoint, to back down.
With their radio not working, Towler leads ten healthy survivors and a badly wounded Private Casey on a stretcher to their objective. As they warily approach the farmhouse, one soldier spots someone inside and throws a grenade, which wounds a Korean woman. The only other occupants are her young son and her adult, part-French daughter Maya. Kincaid and some of the others want to leave before the enemy attacks, but Towler keeps them there.
They repel an attack later that night. Hunter, a Navajo, volunteers to scout the area in place of Towler. They agree on a password. Hunter is captured, but despite being hit repeatedly, refuses to say the password when he is forced toward the outpost manned by Towler and Kincaid. After his challenges are not answered, Towler fires, striking Hunter and some enemy soldiers. After the enemy is repelled, Hunter gives the password. Towler and Kincaid find him; he talks to Towler before dying.
Bracken tries to force himself on Maya. Her scream brings Towler, but Bracken ignores Towler’s order to leave and strikes him. Towler knocks him down, but Bracken remains defiant.
Lazitech, manning the outpost, is the next casualty. At his own request, Casey is carried to a gunport to fight; he dies in the next assault. Towler and Kincaid start brawling when Towler catches Kincaid slacking off afterward, but they break off when they hear a tank approaching. After driving off the accompanying infantrymen with a machine gun, Towler and Kinkaid use kerosene and torches to set the tank on fire. When a tank man opens the hatch, Kinkaid tosses in a grenade. The tank runs over his leg when he jumps off; Corpsman Wade has to amputate it, but the only man who has the right type blood for a transfusion is Towler. The operation is a success, despite Wade’s lack of training.
When a column of tanks is spotted, Towler sends his men and the civilians up the pass, while he goes back and carries Kinkaid to the outpost. Fortunately, friendly aircraft appear and bombard the enemy infantry as they advance, signalling the approach of the battalion.