It was composed by Jerome Kern and Oscar Hammerstein II.
She sings in her German father's beer garden, and has to chase after her sister Nellie when she runs off to become and actress.
Barnett and Schmidt quarrel when show backer and Spanish-American war hero James Day puts the moves on Schmidt and wants her to be his mistress. She almost quits the show, but Barnett browbeats her into performing, and she's a hit.
Later Barnett and Schmidt reconcile, and he composes The Belle of Hoboken for her to star in, and stars opposite her.
Schmidt was played by Helen Morgan in the original Broadway run, and by Irene Dunne in the 1934 film.