How Precious became Hollywood's next big thing

Obese, pregnant teenagers are rarely the subject of hit movies – but the US is falling in love with a heavyweight new star

Its heroine is a black teenage girl made pregnant by her own father and repeatedly beaten up by her mother. She is illiterate, penniless, HIV-positive, and weighs 350 pounds. Its setting is a tough district of Harlem, and the plot is relentlessly bleak. It barely even manages a happy ending.

Does this sound like a staggeringly unlikely premise for a blockbuster movie? Yes. Does it also appear to be the antithesis of the feel-good schtick that generally achieves Oscar glory? Again, yes. But as Hollywood braces itself for Awards Season, there's only one word on the lips of pundits: Precious. And the film's previously unknown star, Gabourey Sidibe, is already on her way to becoming a household name.

Sidibe is untrained. She won her part at an open audition while she was working at a call centre, with little faith that her dreams of acting would be realised. After all, she looks unlike most Hollywood A-listers. Despite initial nerves about the part, though, she has won rave reviews for her performance. "I think people look at me and don't expect much," she said. "I expect a whole lot."

Expectations will be higher in future. The independent film, adapted from Push, a novel by the African-American author Sapphire, has swept the boards at almost every major film festival, from Sundance, to Cannes, to Toronto. It has prompted 15-minute standing ovations, is making stars of its rag-tag cast, and is being widely dubbed this year's Slumdog Millionaire.

On Friday, Precious will go before its most demanding audience yet: the popcorn-scoffing public. Amid a deafening buzz, and after the most positive reviews of any new movie in several years, the film will finally arrive in the only testing ground that really counts: America's cinemas.

From there, if form is any guide, we can expect it to become an international sensation, with a place in history underlined by gold statuettes and teary acceptance speeches. Sidibe is in the running. And director Lee Daniels could be 2010's Danny Boyle. Not bad for a movie that struggled to find backers and was made for a paltry $10m (£6.255m). Not bad for a film so harrowing that one of the many writers singing its praises warned that it "gives the word 'difficult' a whole new meaning".

Precious is the appallingly sad story of Claireece "Precious" Jones, a black schoolgirl from a violent family who has reached the age of 16 without being able to read or write. Repeatedly beaten up and sexually abused at home, she is offered a stab at happiness via a special-needs school and a selection of helpful social workers.

The film has an exotic collection of co-stars, including the comedienne and chat-show host Mo'Nique as Precious's heartless mother, the musician Lenny Kravitz as a doctor, and a make-up-less Mariah Carey as a brilliantly pitched social worker.

"People say to me, 'You are so ugly in this movie,' and I take that as a compliment," Carey recently told the New York Times, when asked to explain the remorseless realism of Precious. "During the filming, I tried to sneak some blush, but Lee caught me. He rubbed my cheek and said, 'Take that off'."

Though it boasts none of the sweeping focus or uplifting sense of redemption of a classic Oscar contender, the film was an instant sensation when it premiered at Sundance, leaving the majority of viewers in tears. It underlined both its popular and critical appeal by scooping the Audience and Grand Jury Awards.

Shortly afterwards, following a bidding war that remains the subject of a legal battle involving Harvey Weinstein (who claims that he entered a verbal contract to buy it), the film was sold to the distributor Lionsgate. Oprah Winfrey and Tyler Perry, the two biggest names in black entertainment, came on board as executive producers.

From there, Precious continued its onward march to Toronto, where it won the People's Choice award (one of six gongs it has so far picked up) and Cannes – where after the closing credits at the premiere rolled, it lead to a standing ovation that lasted for almost 20 minutes. "They wouldn't stop clapping," said Daniels, whose most famous previous film was Monster's Ball (for which Halle Berry won an Oscar in 2002). "I'm a director; after six minutes, I'm saying, 'please sit down.' But I'm also a producer, so I'm thinking, 'what's the record? Can we break the record for the longest standing ovation at the festival?'"

The big question for pundits is whether it can maintain its favouritism in the four months that remain before the Academy Awards sweep into town. "It might not fit the classic profile, but Precious is the film that we 'Oscarologists' have known all along isn't just a contender, but is perhaps going to be the front runner for best film," says Tom O'Neil, who writes the influential Gold Derby blog for the Los Angeles Times.

"It's really dark. It's about non-heroic people doing terrible things to each other, and there's not even a happy song and dance at the end. But it delivers a knock-your-block- off emotional wallop. It came from nothing, and now it has some major disciples."

Though the film is "anti-Hollywood", and deals with tricky themes such as incest, racism, and social deprivation, O'Neil says Lionsgate are mounting a canny campaign in pursuit of prizes, hiring not one but two of Hollywood's best-known awards-season PR experts, Amanda Lundberg and Lisa Taback.

"They are two of the most dynamic seven or eight campaigners in the business, and to have them working together on a film is a big deal. No film has won without a proper campaign since American Graffiti 30 years ago, and they are pushing it hard. Those girls must ring me three times a week."

For now, even setbacks seem to help the film's outsider appeal. Mo'Nique has been failing to attend film festivals to promote Precious (reportedly demanding payment for such duties). Traditionally, that would ruin her chance of a Best Actress gong. But in a country tired of the saccharine conventions of showbusiness, the gesture – like the film – may yet succeed in capturing the moment.