In Seoul, as invasion from the Communist north appears imminent, experienced American military men like Army colonel Steve Janowski and Col. John Parker of the Air Force, work together to help South Korea prepare for war. Dedicated United Nations nurse Linda Day, however, opposes using military force and freely voices her opinion to Steve. Despite their political differences, Steve is attracted to Linda, and when an airborne sniper starts shooting at them outside their hotel, he shields her body with his. Unnerved by the intimate contact, Linda informs Steve that her name is "Mrs. Day." Soon after, while conferring with John at an airfield, Steve spots Linda, who intends to accompany the American military, and carries her against her will to a Japan-bound evacuation plane. Moments after the plane takes off, the airfield is bombed by North Koreans in Russian-made airplanes. Later, in Japan, John learns that he and other Air Force pilots are to fly missions in Korea and bids his supportive wife Mary goodbye. The first days of the war do not go well for the South, and Steve feels compelled to take over a platoon that has lost its commander. Working with John, Steve and his men succeed in destroying North Korean tanks and are pleasantly surprised when Australian pilots join the effort. During another enemy encounter, Steve is wounded and flown to a hospital in Japan. On the day of his release, Linda visits and thanks him for saving her life at the airfield. Steve and Linda make a dinner date, and when he arrives at her apartment, Linda admits she is a widow. After enjoying Linda's home cooked food, Steve tells her that she is the first honest woman he has ever met and kisses her. Later, Steve presents Linda with an engagement ring, but she turns him down, revealing the grief she suffered when her husband was killed in battle during World War II. Although Steve understands Linda's reluctance to marry a soldier, he returns to Korea broken-hearted. At the North Korean border, Steve reunites with his platoon, while Linda and other United Nations workers struggle to help refugees who are streaming in from the north. When Steve realizes that disguised North Korean soldiers have hidden themselves among the refugees, he orders a person-by-person inspection, which causes a significant back-up. While John drops leaflets on the refugees from his plane, asking them not to cross, armed Communist soldiers force the crowd to push forward. Hoping to scare the refugees, Steve directs his men to fire rounds over them, and when that tactic fails, orders a full-scale assault. Linda witnesses the attack, during which many refugees as well as Communists lose their lives, and angrily condemns Steve. Later, in Seoul, Linda runs into John, who tells her that Steve had no choice and shows her photographs of captured Americans tortured and killed by Communists. Filled with remorse, Linda asks John to convey her apologies to Steve, then goes to a church to pray for forgiveness. Back at the front, Steve presents a plan to stop the Communists' supply route by launching a raid in North Korean territory. Despite the risks, the commanding generals approve Steve's idea, and during the night, Steve's platoon sneaks across the border and attacks the first supply truck that comes along. The disabled truck is left in the road, blocking the next truck, which Steve's men also attack. By morning, the entire supply convoy is jammed up on the road, and John and his men begin an aerial assault. Soon, however, Steve's platoon is surrounded by North Korean soldiers, and a fierce battle ensues. That night, when word comes that ammunition for the now-defenseless platoon will not be flown in until daylight, John volunteers to drop the load in the dark. John completes the delivery, but his plane is hit, and he is killed when his parachute catches on fire. Despite John's death, the mission is a success, and Steve learns he is to be promoted to general. As a combat-weary Steve is leaving the battlefield, Linda finds him and begs his forgiveness. Steve calmly informs Linda that someday soon she will be his wife, then heads off for his next mission.