Kristen Stewart, Chanel’s newest campaign model, will star in a film directed by designer Karl Lagerfeld for the French fashion house’s upcoming show.

The story, conceived by Lagerfeld, offers a fictional, behind-the-scenes look at a biopic in the making about founder Gabrielle Chanel, WWD reports.

Stewart portrays an actress impersonating the designer as a young woman. Geraldine Chaplin, who has played Chanel in previous Lagerfeld films, is in the movie as well. Lagerfeld filmed the project last month in two days at director Luc Besson’s Paris studio.

Lagerfeld said Stewart “played it really, really mean.” “You only see her in tests and she’s complaining about everything,” he told WWD. “She’s mean with the director; mean with the producer.”

Lagerfeld also came up with the dialogue, costumes and casting. “They make so many movies about Chanel, why can’t I make one?” he said.

Lagerfeld is the head designer and creative director of Chanel, Italian house Fendi and his own label.

Stewart has shot her last few feature films in France. She recently became the first American actor to win a Cesar (France’s Oscar equivalent) for Olivier Assayas’ “Sils Maria.” She will also star in the director’s next project, “Personal Shopper” — a Paris-set, English-language ghost story in the fashion underworld.

The Métiers d’Arts show, where the Chanel movie debuts, will take place on Dec. 1 in Rome.