It was composed by Jerome Kern and Oscar Hammerstein II.
She is supposed to star in composer Sid Barnett's next stage musicals/operetta, The Love Story. But Barnett becomes enamored of amateur Adeline Schmidt, and insists on her in the starring role. Elysia is understandably angry and show backer Rupert Rockingham pulls out. But Barnett finds a new backer, James Day, and the show goes on.
Later we learn that Elysia is a spy for the Spanish!
Elysia was played Winifred Shaw in the 1934 film. The character was either not in the original play, or had a different name.