Writer Kenneth Lonergan had a surprise hit twelve years ago with the movie You Can Count on Me. His follow-up project, Margaret, was filmed in 2005 and has been stuck in a post-production hell ever since. For the most part, films that generate production controversies are not worth seeing; studios sit on them for a reason. (Coppola’s Apocalypse Now is the most significant exception I can think of: The production process was a nightmare, but the film’s status as a masterpiece grows by the year.)

Margaret has finally been released, and it’s a powerful and well-acted drama that deserves its liberation from captivity in the vaults. Anna Paquin plays an Upper West Side high-school girl who inadvertently occasions a bus accident in which a woman is killed, and spends most of the film dealing with the emotional consequences. Her difficulties, very unusually for a film about an adolescent, are not romanticized; this is not yet another “tender coming-of-age story” in which Innocence comes to terms with Adult Responsibility. If anything, it is a bracing reminder that in facing moral and psychological problems — in creating their own characters and self-images — teenagers and adults in our society are basically in the same boat. The negative way in which this is usually phrased is “the infantilization of our culture”; a less prejudicial way of putting it would be that the process of growing up starts a lot earlier than it used to, but is slower, and never really stops.

The title remains unexplained for a quite a long time in the film; when it is finally revealed to be a reference to Gerard Manley Hopkins’s poem “Spring and Fall,” this comes as a welcome jolt. (One of Hopkins’s best, it’s an unsparing depiction of the roots of all human grief.) Strangely, while in one sense the film is longer than it needs to be — interstitial scenes of New York City are too long and add little, and might just as well be file footage — at the same time the viewer gets the feeling that much interesting material about the supporting characters has been left out. (Matt Damon gets some decent screen time as one of the girl’s teachers; Matthew Broderick gets too little, as another teacher; John Gallagher Jr. and Kieran Culkin are, in different ways, heartbreaking in vanishingly brief appearances as her love interests.) But Paquin is terrific in the lead, and the fact that one leaves the movie curious about some of the other characters indicates that the film has succeeded in creating a world of depth around her.

The film is playing in NYC at the Cinema Village; if you’re interested in finding out when it might come to a theater near you, please consult the movie’s website.