BERLIN—A new adaptation of writer Denis Diderot's 18th-century novel "The Nun" is making its debut at the Berlin film festival, featuring French star Isabelle Huppert as a convent's mother superior.

The movie, directed by Guillaume Nicloux, is one of 19 competing for the Berlin festival's top Golden Bear honor.

The story centers on a young woman, played by Belgian actress Pauline Etienne, forced by her family to enter a convent, where she suffers harassment.

Huppert's long list of credits includes "The Piano Player" and "Madame Bovary." She said ahead of the new film's premiere Sunday that her latest role offered the challenge of avoiding caricature.

"It was very easy to go behind the caricature," she said. "She's a superior mother, but she has nothing superior."