In Rome, Italy, concert pianist Manina Stuart and manufacturing tycoon David Lawrence pick up airline tickets at the same office, but take no notice of each other. Manina and David coincidentally meet later aboard the same U.S.-bound flight, and when the plane lands in Naples because of engine trouble, Manina and David go off sightseeing together. David, who is estranged from his wife Catherine, and Manina, who is single, are delighted by each other's company. When they miss their plane by a few moments, they decide to stay in Naples for a few days. After sightseeing in Pompeii and Capri, David admits that he was traveling alone because he had lost his identity and become unfamiliar with his family after working so many years building his turbine factory. Although Manina and David fall in love, Manina insists they remain platonic friends, and David admits that Catherine, who had initially agreed to his request for a divorce, recently sent him a letter saying she had changed her mind. The next day, David and Manina prepare to return to the United States and are stunned to read a newspaper account about their previous flight, which went down in the Mediterranean. When they see that their names are listed among those presumed dead, David and Manina realize that they have been given a second chance at happiness. David and Manina rent a villa in Florence, and agree to give up their respective careers in order to be together. In the United States, meanwhile, Catherine and her son, David, Jr., mourn David's passing, and their attorney, Charles Morrison, informs Catherine that just prior to the plane accident, David made a large withdrawal from his account for an Italian woman named Maria Salvatini. Although Catherine admits that her marriage was in trouble, she is now distraught because she will never know if David was returning because he loved her, or merely to fulfill their marriage contract. Although David and Manina live in idyllic happiness, Manina's piano mentor, Maria, believes they are selfish and cowardly. She nevertheless remains close to Manina and disburses David's money as needed. Catherine decides to vacation in Italy with David, Jr., and goes to see Maria, believing that she was the "other woman." Manina is present when Catherine arrives and is disturbed when Catherine reveals that she feels responsible for David's death because he was returning to her when his plane crashed. Neither Maria nor Manina reveal the truth, but David, Jr. recognizes Manina from the newspaper reports about the accident, and later he and Catherine realize that David must be alive and living with Manina. Catherine's only response to the news of David's betrayal is joy that he is safe. David launches a project to create a dam for an arid Italian countryside, but is soon forced to abandon the idea because it would mean revealing that he is alive. Manina sees his disappointment and goes to see Catherine, but finds only David, Jr. in their hotel room. David, Jr. tells Manina that he and his mother know the truth and are returning home. He then gives her a letter for his father, who he bitterly insists no longer exists. That night, David reads the letter in which Catherine has written that she will grant him a divorce. Freed by this news, David renews his dam project, while Manina accepts a New York concert date, and prepares to return to the United States with David. Although Manina is glad to return to her career, she harbors a sense that her relationship may not survive the change. Back home, David thanks Catherine for her compassion and reveals that he is confused. Although Manina's Carnegie Hall performance of Rachmaninoff's Concerto Number 2 is a success, she books a flight for South America, where she is scheduled to play, and informs David that their pasts are too real to ignore. Unable to endure a love built on deception, Manina leaves David at the airport.