Lily Mars is a 19-year-old girl from small town
Indiana, who aspires to become an actress on
Broadway. She visits her next-door neighbor Mrs. Mimi Thornway hoping her son John, who is a Broadway producer, will give her a part in his latest touring production. However, John refuses to meet with her, and as Lily listens on, he calls her an amateur. Lily then steals John's play
Let Me Dream and phones him to arrive at her house to retrieve it. There, Lily performs a rendition of
Lady Macbeth's
soliloquy. Unmoved by Lily's performance, John harshly criticizes it before she returns his play. Lily antagonizes John once more outside of Mrs. Thornway's window, as playwright Owen Vail and Russian actress Isobel Rebay look on. John, in frustration, gives Lily free tickets to his play and promises to spank her if he sees her again. After the play, Owen invites Lily to the afterparty, where John chases Lily around until she performs an impromptu swing number. Lily peacefully leaves and returns to her bedroom in tears. In response, Lily's mother encourages her to leave for New York. In New York, Lily sneaks into a Broadway theater and watches a rehearsal for John's play. Lily falls asleep during the rehearsals, and she is discovered by Frankie, a
charwoman who too dreamed of becoming an actress. Frankie encourages Lily to pursue her dreams. The next day, during rehearsals, Lily tries dancing with the show's chorus line until she faints from hunger. Moved by Lily's determination, John takes her to lunch and allows her into the chorus line. He also arranges her living accommodation at a boardinghouse. Meanwhile, Isobel complains about the play's third act and senses John's growing affection towards Lily. As Owen and John rewrite the act one night, Lily arrives in John's office and suggests her own ending. John and Owen incorporate Lily's revisions into the third act. Despite Owen's warning that he is growing too close to Lily, nevertheless, John casts her as a chambermaid. Two weeks later, John and Lily attend a nightclub where Lily performs a number on the club's stage. There, she imitates Isobel's accent, as Isobel recoils in embarrassment and leaves the club. The next day, Isobel quits the play and John cast Lily as her replacement, as he has fallen in love with her. As Lily rehearses her part, she phones her family and invites them to the opening night. However, John decides Lily is miscast and rehires Isobel. Lily leaves the theater, feeling discouraged and returns to her apartment where her family has arrived. Motivated by her family's encouragement, Lily returns to the theater and makes her debut performance. John thanks Lily for returning, and writes his next show ''When There's Music'' for her. Lily, now a star in her own right, performs a musical number with Tommy Dorsey and his orchestra. ==Cast==