After auditioning for a radio part, singer Mary Barrett informs her parents that she is leaving New York City to study music in Milan, Italy. Mary gets a job at the Cafe Roma, where the eminent Giulio Monteverdi hears her sing. Giulio promises to make Mary a star if she will allow him to control her life and mold her, but without the possibility of romance. Soon, Mary is ready for a tour of provincial opera houses, and Giulio helps her to overcome stagefright. After several years, Mary begins to tire of Giulio's dominance and discipline. In Vienna, Mary and Giulio meet one of his old pupils, Lally, who angered Guilio when she tried to engage him in a romance. Mary becomes jealous and pretends to have laryngitis, and Giulio goes to a different hotel. Mary believes Guilio has gone to Lally, and so visits Bill Houston, a longtime friend who has proposed marriage. After a day of throwing fruit at her posters, Mary decides not to sing that night. To persuade her to go on, Giulio first claims that Lally will take her place and then proposes to her. Mary's performance of "La Barrett" from Bizet's Carmen wins her an invitation to the Metropolitan Opera, but Giulio insists she is not ready. Bill then leaves for New York, and tells Mary he does not belong to her kind. Upon returning to a dinner that Giulio has prepared for Mary, Lally lies to Mary, saying that she is still involved with the impresario. On the night of her debut in Madame Butterfly , Mary is too nervous to go on stage, until she sees Giulio in his usual place in the prompter's box. A friend has told Mary of Lally's escapade, but she had been too proud to call Giulio on her own.