At a time when the MacLaines and Dunaways and Fondas are tiresomely bemoaning the scarcity of good female roles, France's Isabelle Adjani has, in one month, been nominated for a Best Actress Oscar for her second movie, wrapped up the filming in Paris of her third and commuted to Amsterdam to begin her fourth. And she hasn't turned 21 yet.

What makes Adjani the belle de jour of European cinema is her morbidly compelling performance as Victor Hugo's neurotic and self-destructive daughter in The Story of Adèle H., for which she has already won a New York Film Critics award. Director François Truffaut wrote the script himself five years ago but had waited to cast the right actress for the part. When he saw Adjani combine adolescent sensuality and innocence in a comedy called The Slap, he decided, "I wanted to shoot with her right away, urgently."

For Adjani, working with Truffaut meant giving up a stage career that had already marked her as France's most promising classical actress. At 16 she became one of the youngest women ever to join France's temple of theater, the 296-year-old Comédie Française. But when a Comédie role conflicted with Adele H., Adjani quit the group in a cause célèbre, spurning a 20-year contract that would be a lifetime's ambition for any other French actress. To Adjani, "It's like asking, 'Will you love the same person in 20 years?' "

"I'm a fanatic, a very dangerous person," Adjani explains of her high-voltage career. "Intensity is all that counts for me. I have very little time, so I accelerate my process of concentration. When work keeps me busy, I feel like I'm drunk. I don't ask for anything more. It's my kind of eroticism."

Adjani will surely be the only nominee at the Academy Awards ceremony who is still living with her parents. She grew up in the Parisian working-class suburb of Gennevilliers, raised by a German mother and a Turkish father who ran a garage. In the classic Hollywood cliché, Isabelle was stopped on the street at the age of 14 by a French TV producer who launched her career.

In many ways, Isabelle is still more a petite French schoolgirl than an international beauty. She wears no makeup and knocks around in unglamorously plain clothes. She has kept up her education, passed her baccalauréat, is now auditing classes in philosophy and psychology at the University of Vincennes in Paris. She's fluent in both English and German and actually does read Sartre, Nietzsche and Freud. "All forms of analysis and synthesis interest me," Isabelle says. "Every actor has his own fortress. I'm always in search of myself."

Adjani's introspection and passion for privacy make her an enigma even to her few close friends. She refuses to talk about her family, and a leading man has yet to surface in her young life. (When asked, she replies cryptically, "I'm in love nonstop: one hour, three days, one month.") The French press has awarded her its put-down Prix Citron (Lemon Prize), presumably because she refuses to act like a starlet. In Amsterdam, where she's currently shooting André Téchiné's Barocco, most of the cast stays in a hotel. Isabelle rented an apartment and in her spare hours pedals a bike around the cobblestoned streets. "I've known Isabelle since she was 16," says one good friend. "But I really never know what she is thinking or how she will react."

Isabelle is carefully sorting her post-Adèle H. offers with a fear that stardom "can threaten the artistic side of your work." She dismisses Hollywood as a "city of fiction" and has shown little interest in lucrative parts in multimillion-dollar productions. But she is dickering to co-star in Al Pacino's next picture and is rated a far stronger shot than most foreign actresses to export an Oscar this month in what is the weakest field in years. "I'm not an American," she protests. "I didn't grow up with that will to win an award." The perceptive Truffaut, however, may have the last word on Adjani's future. "France is too small for her," he concludes. "I think Isabelle is made for American cinema."