Opera singer Grace Moore turns to popular music when her dreams of a classical career fail to materialize.

In 1928, in a dressing room at New York's Metropolitan Opera, singer Grace Moore prepares for her debut performance and reminisces about her climb to success: As a child in Jellicoe, Tennessee, Grace is always doing the unexpected, often embarrassing her stiff-necked father, Col. James Moore. In church, where she sings in the choir, the appearance of a handsome young minister inspires Grace to dedicate her life to spreading the gospel. At her high school graduation, she fervently preaches to the crowd who is expecting to hear her sing. Because of the intervention of her aunt, Laura Stokley, who considers herself a fellow "dreamer" and recognizes Grace's uncultivated musical talent, Grace is sent to study music at Wilson Greene School, a conservatory near Washington, D.C. There Grace briefly meets opera star Mary Garden, who encourages her dream to sing opera. Later, during her first public performance at the National Theater, Grace performs in a recital with the famous singer, John McCormack, and although her song is interrupted by the impromptu celebrations of Armistice Day, the newspaper duly reports the musical event. Upon reading the review, Col. Moore is outraged that his daughter is performing on a stage and proceeds to Washington to bring her home. However, by the time he arrives, Grace has escaped to New York with a friend, Ruth Obre, and they take up residence in an apartment with two other young women. After catching up with Grace, Col. Moore reluctantly agrees to support her stay in New York until Christmas. However, when her performance at an amateur "talent night" leads to a singing job in a nightclub, Grace remains in New York. While taking voice lessons with a teacher who encourages loud singing, Grace develops acute laryngitis and loses an opportunity for the lead role in a show. Advised by Dr. Marafioti, a teacher and voice specialist, to resign herself to rest and complete silence for three months, Grace refuses the marriage proposal of her boyfriend, Buddy Nash, a Broadway performer, and moves to a lakeside cottage near Boston that is owned by the wealthy family of Ruth's boyfriend, Bryan Curtis. Alone, Grace spends the winter in silence, and learns in a letter that Buddy is marrying someone else. When she returns to New York in the spring, after not speaking for months, Marafioti confirms that the inflammation in her throat has healed and then teaches her the proper way to sing. Later, Grace gets a role in a show, but her provocative movements to "I Wish I Could Shimmy Like My Sister Kate" embarrasses Col. Moore, and she struggles to convince him that the show is a stepping stone to something greater. The show closes after four weeks, but composer George Gershwin refers Grace to Harry Cort, who is putting on a show in Boston. Although she gets the part, she must contend with its jealous star, Marilyn Montgomery, but Grace's confident stubbornness is equal to Montgomery's tantrums. During rehearsals, Bryan spends time with his family, and he and Grace develop an affection for each other, despite their desire not to hurt Ruth. However, the understanding Ruth has guessed that her boyfriend and best friend have become close and forgives them. Montgomery gets sick after the show opens, and Grace stands in for her. Over the next several years, Grace becomes one of the biggest Broadway stars. In a restaurant one night, Grace finally agrees to marry Bryan, who has waited patiently for her career to stabilize. However, as they are dining, Mary Garden shows up and Grace re-introduces herself. Garden introduces her companion, Otto Kahn, the chairman of the board of the Metropolitan Opera, and Grace remembers that her first dream was to sing opera. Later, at an audition for the Met arranged by Kahn, Grace is rejected by the committee because of her lack of operatic experience. Undaunted, she bets Kahn that she will debut there in two years and accompanies Mary to Europe, leaving behind her Broadway show and Bryan. Two years later, Bryan and Ruth, who are back together, are part of the audience waiting to hear Grace's Met debut. With them are Grace's family, teachers and friends. On cue, the twenty-seven-year-old Grace comes on stage and sings "Mimi" in La Bohéme and afterward takes twenty-eight curtain calls: one for each year of her life, and one to grow on.