 Complete the following phrase:  The film stars Charles Boyer and Danielle Darrieux with René Bergeron, Jean Davy, Jean Dax, Jean Debucourt and Gabrielle Dorziat, and Jean-Louis Barrault in a bit part. The film is based on the real-life story of Crown Prince Rudolf of Austria, his affair with the 17-year-old Baroness Maria Vetsera and their tragic end at 