PHILADELPHIA'S Lee Daniels isn't just the producer and director of "Precious," he's its Capt. Chesley Sullenberger.

As a movie, "Precious" is a perilous ride, one that often feels ready to nosedive, but never does. Against long odds, Daniels brings it to a safe and improbable landing, an outcome that under the circumstances feels like a triumph.

It's hard to believe the movie got off the ground at all - its title character is a poor, illiterate, unglamorous 300-pound African-American girl, both an unwed mother and abused daughter. It goes without saying the movie is independent - you can imagine how far the script would get in Hollywood, once they measured the story against their marketing metrics and demographic quadrants.

Precious is played by an unknown, Gabourey Sidibe, who's given a large and daunting job. She's tasked with pulling us into this harsh story of suffering and striving, and keeping us there, even as the narrative pushes the boundaries of credibility and tact.

Sidibe's an obscure amateur, and yet all around her are celebrities - Mo'Nique, Lenny Kravitz, Mariah Carey - asked to disappear into this strange mixture of redemptive fable and real-life horror movie.

It's tricky material, adapted faithfully by Daniels from the novel "Push" by Sapphire. The book has widely been described (with sarcasm) as an example of pulpy urban lit, but that's wide off the mark. Sapphire, a Brooklyn, N.Y., poet, wrote it in stylized street argot, meant to convey Precious' untutored voice, a technique as old as "Huckleberry Finn," who's mentioned in the book, one that's crammed with literary tributes and allusions.

It's literature that looms as a possible savior for Precious, who's chucked out of public school when the principal discovers she's pregnant. Her choices are life at home on welfare with her monstrous mother (Mo'Nique) or an alternative school for troubled girls, run by a saintly teacher (Paula Patton) who challenges her students to read and write as a means of expression and understanding.

Daniels isn't going for subtlety here - Mo'Nique is terrifyingly cruel, Patton silky and angelic, and he counts on his actresses to bring emotional and psychological legitimacy to their characters. He gets more than he had a right to expect, especially from Mo'Nique. The performance could have been a nightmare, a ghetto "Mommie Dearest," given what she's asked to say and do. She needs to be a monster - that makes us understand how close Precious is to oblivion - but she's also able to suggest, somehow, a backstory that hints at how she got there.

Scenes of Mo'Nique explaining herself to Precious' welfare case worker (Mariah Carey!) are first-rate, and kudos to Carey, a potential distraction who ends up being a significant asset.

Also first-rate are the girls who play Precious' classmates at the alternative school, where troubled girls are encouraged to use journals, poems and stories to make sense of their lives. We've seen this rainbow coalition of at-risk youth before, but we've rarely seen so many potential stock characters register so strongly.

With so many performers contributing so much solid work, it may be time to acknowledge that Daniels knows what he's doing. The guy can handle actors. It was Daniels who produced "Monster's Ball," earning Halle Berry a nomination and an Oscar win. "Precious" may be headed for its share.

The movie has already gotten a boost from TV talk host Oprah Winfrey and actor-director-producer Tyler Perry, who've signed on as executive producers, endorsements that have lead many to conclude that "Precious" amounts to formulaic uplift.

But "Precious" does not fit so easily into either celebrity's brand. It's much harder to pin down, unique in tone and point of view.

Daniels has taken Sapphire's book and toughened it, especially the ending, which eschews Christian uplift, female-empowerment team-building, and pretty much scoffs at the idea that social services can help a girl like Precious.

Precious is determined to make her own way, which makes her either proudly independent, or dangerously alone.