Set in Europe during World War I, the plot focuses on the tragic romance between Frederick Henry (Gary Cooper), an American ambulance driver serving in the Italian Army, and Scotish Red Cross nurse Catherine Barkley (Helen Hayes). Major Rinaldi (Adolphe Menjou) envies their relationship and has Catherine transferred to Milan. When Frederick is wounded in battle, he finds himself in the hospital where Catherine works. They continue their affair until he returns to battle. Now-pregnant Catherine settles in Switzerland, and when her many letters to Henry remain unanswered because his responses are held up by the censors, she assumes he has abandoned her. As the Armistice nears, Frederick journeys to Switzerland to find Catherine, who dies in childbirth with him at her side.