The Firefly (film)

The Firefly is a 1937 musical film starring Jeanette MacDonald and Allan Jones. The film is an adaptation of the operetta of the same name by composer Rudolf Friml and librettist Otto A. Harbach that premiered on Broadway in 1912. The film used nearly all of the music from the operetta but jettisoned the plot in favor of a new storyline set in Spain during the time of the Emperor Napoleon I. It added a new song, The Donkey Serenade a reworking by Herbert Stothart of Frimls 1918 orchestral piece Chanson, which became extremely popular, as was one of the Friml songs, Giannina Mia.

Source: Wikipedia