In Rome, Count Verbano, a handicapped World War II veteran whose wife was killed in the war, is visited by his war friend, American Henry Brent and his daughter Caroline. The count enlists his son Antonio to show the Americans around Rome, despite the teenager's thinly veiled contempt for Americans, whom he blames for his mother's death. Among the sights they visit are the Vatican, featuring the Sistine Chapel and its choir singing "Ave Maria"; the Catacombs of St. Sebastian; St. Peter's; and many artworks by such artists as Michelangelo, Raphael and Botticelli. In addition, Antonio treats them to thrilling accounts of Italian history, including an explanation of the election of Pope John XXIII. Antonio is so openly hostile to the Americans, however, that Caroline asks him to stop acting as their guide, a request that shocks Antonio into behaving more civilly. Exhausted by the teenagers' enthusiasm for sightseeing, Henry retreats to the hotel room, and Antonio and Caroline continue on alone. Along the way, the two fall in love, and Antonio finally realizes that his prejudices are unjust.