A group of war nurses fights to survive the siege of Bataan.

At a U.S. military hospital in Marivèles, on the Bataan Peninsula of the Philippines, overworked Army nurse Lt. Mary "Smitty" Smith, begs her superior, Capt. Alice Marsh, for more nurses. Instead of nurses, Smitty receives nine civilian refugees from Manila. As Japanese forces are moving closer to Marivèles every day, Smitty feels compelled to accept the female volunteers and questions each one about her background. Smitty soon discovers that all of the women are ill-equipped for the front and none has had medical training. After Capt. Marsh warns the group to expect extreme hardship, Smitty, who herself has contracted malaria, orders everyone to take quinine. Working class volunteer Pat Conlin resents Smitty's cool, no-nonsense manner and ignores her order, but is happy to be assigned to the Signal Corps switchboard, where handsome Lt. Thomas Holt works. Later, in the underground bunker that serves as their living quarters, the volunteers share their fears and hopes. After delivering a moving speech about freedom, Sue West, a young, genteel English volunteer, wanders outside. When an air raid begins, Sue's older sister Andra becomes worried, but is prevented from searching for Sue during the attack. Once the bombing is over, the volunteers, Capt. Marsh, Smitty and fellow nurse Flo Norris rush to the hospital, which has been hit. Volunteer Grace Lambert, a former burlesque dancer, is shocked by the dying soldiers but, along with the others, does her best to help. Days later, while Andra goes out to look for the still-missing Sue, Pat admits to the others that she is infatuated with Lt. Holt. When Flo mentions to Pat that Smitty also has feelings for the officer, the ever-cynical Pat is unimpressed. That night, Andra learns that Sue has been found alive, after having spent days trapped in a shelter with several corpses. When Andra leaves to retrieve her sister, Pat lets down her guard and makes friends with her former "enemy," Connie Booth. The well-bred Connie admits to being terrified, but Pat reassures her that she is tougher than she thinks. Andra then returns to the bunker with Sue, who is now deranged and helpless. Although Grace tries to distract the women by performing one of her burlesque dances, Sue's anguished screams unnerve them all. Soon after, Flo reports that the U.S. supply ship was sunk by the Japanese. Another air raid then begins, and the Japanese once again bomb the hospital. After the all-clear sounds, the women run to help the wounded and are surprised when the bombing suddenly resumes. During the second raid, Grace's leg is injured, and Smitty criticizes her for being careless. Angered, Grace tells Smitty that Pat is stealing Lt. Holt away from her, and once alone, Smitty breaks down in tears. Smitty, who is suffering a recurrence of her malaria, is somewhat relieved, however, when Lt. Holt telephones her and reassures her of his love. Seeing the stricken Smitty, Sadie, the company cook, advises her to leave on the next transport to Corregidor, but Smitty angrily dismisses her concerns. Later, Smitty announces that no more supplies are coming in and advises the women that, while General Douglas MacArthur has ordered the Army to "dig in," they are free to leave. After some debate, all of the volunteers, including a transformed Connie, elect to stay. Six weeks later, the women learn that MacArthur has been sent to Australia, ending any speculation that a rescue is imminent. Connie is then shot and killed by a Japanese gunner. Connie's death infuriates Pat, who, in an attempt to bolster the women's resolve, shows them a map detailing the U.S.'s attack strategy. Aware that Pat got the map from Lt. Holt, Smitty is overcome with jealousy and yells at her. Flo then forces the feverish Smitty to lie down, and while resting, Smitty confesses to Flo that she is married to Lt. Holt, but has kept their relationship a secret because of an Army regulation forbidding nurses from marrying soldiers. Smitty also reveals that, as her malaria is terminal, she intends to spend as much time as possible with her husband. Flo suggests that Smitty tell Pat the truth, but Smitty refuses. Soon after, the Japanese begin to close in on the camp, and a desperate evacuation ensues. When word arrives that Lt. Holt has been killed, both Pat and Smitty are stunned with grief. Flo finally tells Pat about Smitty's situation, and while impressed by Smitty's courage, Pat criticizes her for keeping her marriage a secret. Moments later, the women are forced to surrender to the Japanese. As they are exiting the bunker for the last time, Smitty admits to Pat that she was wrong not to tell her about her marriage. Touched by Smitty's honesty, Pat assures her that Lt. Holt was a faithful husband to the end.