The Mozart family lead adventuresome lives in 1763 as they travel from place to place playing music for European nobility. Leopold (Marc Barbe) is a musician and composer whose offspring show signs of being more talented than he ever was. His wife Frau Mozart (Delphine Chuillot) is a beautiful woman who has done a fine job raising their two children, Wolfgang (David Moreau) and Nannerl (Marie Feret). The young boy is a prodigy and has replaced his older sister in the spotlight; he composed an opera at age 12. She wowed her parents as a young child showing a special gift for playing the violin. But now that her brother gets all the accolades and attention, Nannerl must be content to serve as an accompanist for Wolfgang who easily outshines other talented child musicians. She is especially disappointed when her father orders her to stop playing the violin (it is seen as a male realm) and to forget any ideas of composing.

These restrictions propel Nannerl to seek other options. She meets the King's daughter, Louise (Lisa Feret), who immediately casts her as a close friend. This confident and controlling adolescent is very impressed with Nannerl's musical gifts. But the two of them are forced on separate paths when Louise chooses to enter a convent. No matter, Nannerl is treated like a queen by the Dauphin (Clovis Fouin), destined to become King of France one day soon. He has a passionate love of music and asks Nannerl to compose something for him. She is caught up in a swirl of creativity and rewarded when the Dauphin sets up a chamber orchestra to perform her work. Dressed as a man to escape scandal, Nannerl enjoys her moment as a composer appreciated by all.

Mozart's Sister is directed by Rene Feret. It offers us an enchanting story of a gifted young woman's coming of age in a male-dominated time when all roads to her fulfillment as a female musician and composer are closed down. The film contains some exquisite scenes shot inside Versailles and is sweetened by original music by Marie-Jeanne Serrero.