A mother who wants only the best for her challenged daughter faces a number of new and unexpected dilemmas in this romantic drama. Margaret Johnson (Olivia de Havilland) is a wealthy woman taking a tour of Europe with her 26-year-old daughter Clara (Yvette Mimieux). Clara is blonde, beautiful, and charming, but beneath the surface lurks a serious problem -- as a result of a head injury she suffered as a child, Clara is mildly retarded and has the mental capacity of a ten-year-old. While Margaret's husband Noel (Barry Sullivan) has long contended that Clara should be institutionalized, Margaret refuses to hear of it, and she sees to it that her daughter lives as normal a life as possible. While in Italy, Margaret and Clara meet a handsome young man named Fabrizio Naccarelli (George Hamilton), the son of a prosperous local, Signor Naccarelli (Rossano Brazzi). Fabrizio is immediately smitten with Clara, and she seems equally fond of him; since Frabrizio has a spotty command of English and isn't especially perceptive to begin with, he doesn't notice anything unusual about her. Before long, Fabrizio asks Margaret for Clara's hand in marriage; while this would be a big step toward the "normal" life that Margaret has long dreamed of for her daughter, she's not sure if Clara is capable of handling the responsibilities of marriage and parenthood, and she is equally uncertain if she should reveal the nature of Clara's condition to the Naccarellis, even though she knows that it would be terribly unfair for Fabrizio to marry Clara without knowing the truth. Light in the Piazza was beautifully shot on location in Italy by award-winning cinematographer Otto Heller.