In Chicago in 1908, aspiring lyricist Gus Kahn begs music company clerk Grace LeBoy to read some lyrics he has written. Although she brusquely dismisses him, he finally persuades her to look at them, and she advises him that the trick to writing a good lyric is to remember that most popular songs give people a way to say "I love you." Later that evening, Gus, having taken her advice to heart, appears unexpectedly at the house where Grace lives with her parents. The LeBoys invite him to stay to dinner, and while Gus eats, Mr. LeBoy recites from "Songs from the Portuguese" by Elizabeth Barrett Browning. Feeling deeply inferior, Gus departs, leaving his new lyric with Grace, who likes it enough to set it to music. She then offers the song to her boss, but when he refuses to listen to it, she quits her job and sells the song, "I Wish I Had a Girl," to Fred Townsend. With Grace plugging the tune, it sells briskly, but the team's subsequent songs are not as successful. When Townsend suggests that Gus team up with composer Egbert Van Alstyne, he refuses out of loyalty to Grace, until she persuades him of the composer's superior talents by pretending to have written one of Van Alstyne's melodies. Sometime after tenor John McCormack introduces Gus and Van Alstyne's song "Memories," the shy Gus finally gets up the courage to propose to Grace, and the two are married. When Grace announces her pregnancy, Gus entitles a song "Pretty Baby," in her honor. With new composer Isham Jones, Gus goes on to write lyrics for many memorable songs, but when Townsend refuses to publish "The One I Love Belongs to Somebody Else," Grace sings it to impresario Sam Harris, who buys it for his new show. Grace and Gus have a baby boy, whom they name Donald, and Gus temporarily leaves song writing to fight in World War I. After the war, Grace again becomes pregnant, and this time gives birth to a girl, Irene. Gus's reputation grows, and showman Florenz Ziegfeld asks him to write a show. Gus refuses, as he does not want to leave Chicago for New York, but Grace again intervenes and accepts the offer for him. Gus does not immediately get along with Walter Donaldson, the show's composer, but manages to write a lyric for "Carolina in the Morning," while sitting with Donaldson and his girl friend, Frankie Mason, at the race track. However, Gloria Knight, the Ziegfeld star who will sing the number in the show, dislikes the song and decides to teach Gus about sophistication. The result is "Love Me or Leave Me," which Gus has Gloria sing over the phone to Grace in Chicago. When the new show, Whoopee! , opens, Grace makes a surprise visit to New York, where Gloria assures her that despite her efforts to seduce Gus, he cares for no one but his family. Sometime later, Gus and Donaldson quarrel and end their partnership. After the stock market crash of 1929, Gus cannot get work and Grace encourages Gus to call Townsend in Hollywood, where he now works. Gus's pride will not allow him to beg for work, but as usual, Grace takes matters into her own hands, and Gus soon leaves for California. The effort to conform to a formulaic approach to movie music makes him so unhappy that he has a heart attack. Grace flies out and encourages him to keep working, even though his doctor has warned him to take it easy for health reasons. Gus still cannot find a composer he likes, so Grace sends for Donaldson, and reunited, the team writes "I'll See You in My Dreams." In 1939, Donaldson throws a testimonial dinner for Gus, who thanks Grace for her help in his career, and publicly tells her how much her loves her. The audience then asks Gus to sing the first song he ever wrote, and when he claims that he cannot remember it, Grace pulls out his handwritten lyric for "I Wish I Had a Girl," which she had saved all through the years.