Prince Klemens von Metternich orders Friedrich Gentz, one of his aides, to keep the Duke of Reichstadt---Napoleon Francois Joseph Charles---son of Napoleon and heir to the French throne, from thinking about French politics. Gentz enlists the help of ballerina Fanny Elsser, all the rage in several European capitals, to keep the Duke distracted.

Lilian Harveyas Fanny Elßler
Willy Birgelas Hofrat Friedrich Gentz
Rolf Moebiusas Duke of Reichstadt
Liselotte Schaakas Therese Elssler - Fannys Schwester
Ernst Karchowas Dietrichstein
Walter Werneras The Maestro Foresti
Ernst Sattleras Kammerdiener Lindner
Hubert von Meyerinckas Polizeipräfekt