In 1940, renowned Polish pianist Stefan Radetsky tinkers at a piano in a London hospital, his memory gone. As the doctors discuss how to cure Stefan, he begins to play his famous composition "The Warsaw Concerto." The piece jogs Stefan's memory, and he remembers a period, two years earlier, in war-torn Warsaw, when he was composing the then-unfinished concerto: Drawn by the sound of music, American war correspondent Carole Peters picks her way across the rubble-strewn streets to Stefan's apartment. When Carole chides him for playing the piano instead of defending his country, Stefan replies that he is a fighter pilot, but his squadron has been decimated and the Polish planes lack fuel to fly. Later, as Poland totters on the brink of surrender to Germany, Stefan's company plans a final suicide mission over Germany. Deciding that Stefan's musical gifts must not be squandered on the atrocities of war, his commanding officer instructs American pilot Mike Carroll to fix a draw of the cards to insure that Stefan is one of three men chosen to fly to safety in Romania. As Stefan flies one last time over Warsaw, he vows to return one day. Six months later, Stefan and Mike are in New York on a charity concert tour. Carole comes to the concert to interview Stefan, but he fails to recognize her at first. Later, remembering their night in Warsaw, he invites her to dinner. That evening, Stefan speaks of his dream of defending his country, and Carole protests that he must not endanger his talent by putting himself in the path of war. That same night, Stefan proposes to Carole and they are wed. After telling her father about her marriage, Carole drives with the Stefan to the family's country house. The next morning, Carole is awakened by a phone call from Mike, who has tracked them down to notify Stefan that it is imperative he return to the city the following day because his concert date has been moved up. Mike also asks Carole to tell Stefan that he has enlisted in the Polish Squadron of the Royal Air Force, but Carole, fearful that Stefan will be encouraged to enlist, withholds the information from him. That night, Stefan plays his unfinished concerto for Carole and tells her that he will never be able to play the piece without thinking about her because it represents their story. Upon returning to New York, Carole begs Mike to keep his plans secret from Stefan, and he consents. One month later, as the concert tour traverses the United States, word comes of Germany's invasion of Belgium. Recalling the devastation of Warsaw, Stefan resolves to return to England and rejoin the war. Upon learning that Carole has kept Mike's enlistment secret, Stefan feels betrayed, but Carole convinces him that his responsibility is to preserve his talent. Stefan returns to New York just as the Germans invade Paris, and becomes conflicted about where his duties lie. He consults Carole's father, who encourages him to rejoin the war in Europe, but when he informs Carole of his decision, she spitefully tells him about the fixed draw that guaranteed his safety in Romania. Her tactic backfires, however, as Stefan's resolve is strengthened. For his farewell concert, Stefan plays the now completed concerto. Fleeing the concert in tears, Carole decides to reconcile with Stefan, but she is too late, for he has already left for Europe. Stefan rejoins Mike in the ranks of the Air Corps, where Mike's attempts to reconcile him with Carole cause the two friends to argue. When Mike fails to return from a mission, Stefan goes to his quarters to sort out his possessions and finds a letter from Carole, telling of her remorse and plans to sail to Europe. While flying another mission, Stefan runs out of ammunition and rams his plane into a German fighter. His thoughts returning to the present, Stefan continues playing his concerto, and when he looks up from the piano, he sees Carole. He speaks her name and they embrace.