Only a few days before his wedding, Michael Hamilton (Clark Gable), a Philadelphia lawyer, travels to Naples in southern Italy to settle the estate of his late brother, Joseph, with Italian lawyer Vitale (Vittorio De Sica). In the opening narration, he states that he "was here before with the 5th US Army" in World War II. In Naples, Michael discovers that his brother had a son, eight-year-old Nando (Marietto), who is being cared for by his maternal aunt Lucia (Sophia Loren), a cabaret singer. Joseph never married Nando's mother but drowned with her in a boating accident. Joseph's actual wife, whom he had left in 1950, is alive in Philadelphia. Michael discovers to his dismay that his brother spent a fortune on fireworks. After seeing Nando handing out racy photos of Lucia at 2 a.m., Michael wants to enroll Nando in the American School at Rome, but Lucia wins custody of the boy. Despite the age difference, romance soon blossoms between Michael and Lucia, and he decides to stay in Italy.