Alma Deutscher, 11, from England performs The Wiener Musikverein in Vienna on Oct 6. An opera the girl wrote, Cinderella, will premiere in the city on Dec 29. [Photo/Agencies]

It takes place in an imaginary country she calls Transylvanian, populated by imaginary composers.

Her favorite, Antonin Yellowsink, wrote one of the more melancholy melodies－"and I stole it", she joked.

But according to Anna Voshege, an Australian singer who plays one of the stepsisters, what Alma composes is anything but childish.

"I heard the music before I knew she was 11. I was really quite shocked. Some of the nuances in that music are really very special, very intricate," Voshege said.

"It's very beautiful music and she is far beyond her years," she said.

Alma's father, Guy Deutscher, first realized his daughter was out of the ordinary when she asked, at age 2 or 3, "'How can music be so beautiful?'" he recalled.