German musical-comedy favorite Willy Forst is writer, director and star of Operetta. Produced in 1940, the film did not receive an American release until long after WW II had ended. The story concerns 19th-century impresario Franz Jauner (Forst), who battles with opera diva Marie Geistinger (Maria Holst) to win the hearts and minds of Viennese music lovers. Geistinger loses the battle, but wins the love of Jauner. Amidst several well-staged operetta vignettes, the film offers impersonations of such musical greats as Johann Strauss and Franz von Suppe. The latter character is portrayed by opera singer Leo Slezak, the father of actor Walter Slezak and grandfather of soap-opera star Erika Slezak.

An attempt to cover several decades of the Viennese operetta scene and some of the main personalities and events, tied together with a somewhat unlikely and dysfunctional love story.