CHARLOTTESVILLE, Va.--A new film named "Thirteen" tells the story of a year in the life of a teenage girl. If that causes any preconceived notions to spring into your mind, sweep them out again. This film is not about dating boys, about watching MTV, about popularity at school, about sitcom one-liners, or even about alienation and shyness. It is about a quiet and private young woman named Nina, and about the mysteries of the human personality.

I walked into the screening of "Thirteen" here at the Virginia Festival of American Film knowing next to nothing about it, except that it had been filmed in nearby Richmond and won a prize at the Berlin Film Festival. The lights went down, and at first the film felt like a cinema verite documentary, narrated by Nina's mother, Lillian, who observes with concern but not alarm.

Nina is not a talkative girl. She keeps to herself. One senses that her imagination is so populated that outsiders are not needed. One also senses that at some point in her life she put up a wall. Not one of those unscalable walls of mental illness, but a temporary wall, like you find around construction sites.

Nina and Lillian live within the rhythms of an extended African-American family, where telephone calls form a network to keep everyone updated on everyone else, right down to distant cousins and the relatives of ex-spouses. Neighbors and relatives are in and out of the house all day, and in times of emergency they turn up unbidden to see how they can help.

For Lillian, Nina is a fascinating case study. She observes her, speculates about her, reports on her activities. One day Nina disappears, and for four days there is a search--but "Thirteen" doesn't traffic in the false alarms of conventional cinema, and there is no artificial crisis. We know all along where Nina has gone. And the manner of her return supplies the trigger that all moviegoers know: That moment when you stir and say to yourself that this is going to be a good film.

The movie contains a lot of humor, quiet and understated. Nina wants to buy a car. She is 13 and cannot drive, but Lillian accepts her ambition as Nina works at every job she can find to make money. She's blunt and direct with her employers, isn't shy to apply for grown-up jobs, asks for a higher salary, studies car magazines. Boys aren't in the picture yet. She is a free-standing, self-contained original. There is no attempt to ingratiate her with the audience.

The movie stars Lillian Folley as Lillian, and Wilhamenia Dickens as Nina. In real life, Nina came to Lillian as a foster child, and was adopted four years ago. They do live together in the house we see. But the characters in the movie are not quite the people they are, and the director is the third collaborator, using them to reflect larger truths about relationships.

All of this provides an incomplete picture of the film, I know, but it doesn't reduce easily to description. The movie was directed by David D. Williams, who earlier made a documentary about Lillian, a neighbor, and then began this film, which is fiction based on the facts of the two womens' personalities. It's not exactly improvised, he said, there was an outline, but no written dialog, and many of the moments occur spontaneously. Like Werner Herzog's "Little Dieter Needs to Fly" and Nicholas Barker's "Unmade Beds," it uses actual lives as materials to be shaped into fiction. The result is one of the truest films I've seen about the ebb and flow of a real relationship. Not one pumped up by a plot and a crisis and resolution, but one in which time flows and small changes accumulate. It's not a question of coming to the conclusion, but of starting a new chapter.

"Thirteen" focused my attention the way the films of Robert Bresson do, challenging me to look into Nina and guess what she was thinking, and what deeper feelings were manifesting themselves in her comings and goings and her dream of a car. When will the film open in theaters? Hard to say. It doesn't have the hooks that distributors look for. No easy pay-offs or dramatic revelations. People reading about it might not think they want to see it. People seeing it will remember it as one of those times when a movie put aside the artifice and razzle, and looked solemnly at the beauty and puzzlement of life.