Set in Chicago during World War II, three Irish Catholic sisters--Kitty, Louise, and Tish Heaney, say good-bye to their boyfriends at Union Station as they head off to war. Over the next three years, the sisters learn what it means to sacrifice during wartime. Kitty takes on an exhausting job at Douglas Aircraft; Louise, deeply in love with her boyfriend, keeps her worries to herself while writing him upbeat letters full of the news of home; and Trish spends her weekends at USO dances, promising to write to every soldier she meets.