It's always nice to be an overnight sensation, even if you're bald and old enough to have been inspired to become a fashion photographer after seeing Michelangelo Antonioni's Blow Up in the 1960s. Just ask Paul Haggis, the Canadian-born writer-director who's so hot right now he has Steven Spielberg pitching him story ideas and Dustin Hoffman taking him to lunch. What makes the 52-year-old's success so satisfying is that he earned it the hard way.

After years of toiling in relative obscurity in TV, where he was beloved by critics but spurned by audiences - the show he considers his greatest achievement, EZ Streets, was canceled the week it debuted - he has suddenly emerged as Hollywood's go-to guy for dark, difficult material.

His adaptation of Million Dollar Baby for Clint Eastwood won the Oscar for best picture. He has just finished the script for Eastwood's next film, Flags of Our Fathers, the troubling true story of the six men who raised the flag on Iwo Jima.

He's also writing with Spielberg a script he will direct at DreamWorks and has another directorial role in pre-production at New Line. He's also writing Death and Dishonor, based on a Playboy article about a career army officer whose soldier son is murdered by members of his platoon after returning from Iraq.

He's a filmmaker with a knack for hitting a nerve. ``My agent showed the story to me after I told her, `If you read something political and volatile that will never get made anywhere else, send it to me,''' Haggis explains.

As he puts it: ``If you're not provoking somebody, what's the point?'' After conservative critics attacked Million Dollar Baby, painting it as a right-to-die movie, Haggis jokingly apologized at an awards banquet for ``turning Clint Eastwood into a communist. I only tried to turn him into a socialist and overshot a bit.'' But if he provoked ire on the right with Million Dollar Baby, he's all set to upset the left with Crash, a provocative drama he co-wrote and directed.

A caustic portrait of Los Angeles as a melting pot boiling over with racial and ethnic strife, the film is about the thing that most defines the city - its contradictions. Populated with an ensemble that includes Don Cheadle, Matt Dillon, Sandra Bullock, Terrence Howard, Ludacris, Brendan Fraser and Larenz Tate, it views Los Angeles in much the same way that David Milch sees Deadwood, as a town given over to rough talk, seething resentments and the unsettling specter, as Haggis says, of ``wonderful people doing horrible things and horrible people doing wonderful things.''

Co-written with Bobby Moresco, the film captures the raw language and underbelly of multicultural Los Angeles that rarely shows up on the local news, much less in Hollywood films. A petty thief arrives at a chop shop, eager to sell a stolen van, only to discover a huddle of Asian immigrants padlocked inside the vehicle. The shop owner, a Russian immigrant, says he'll take the refugees, too. ``You want to buy these Chinamen?'' the hustler says incredulously. ``Don't be ignorant,'' the Russian replies. ``They're Thai or something. How much you want for them?''

The movie picks at the scabs of a city vexed by ethnic dread. A Mexican mocks a Korean's fractured English. Arguing with an Iranian man, a gun shop owner growls, ``Yo, Osama, plan the jihad on your own time!'' When a black man, making love with a Hispanic woman, is interrupted by a phone call from his mother, he says, ``Ma, I gotta go, I'm having sex with a white woman,'' later telling his lover, ``I would've said Mexican but it wouldn't have ticked her off as much.''

Built around a dozen or so interlocking characters and storylines, the film owes its genesis to an incident in the 1990s when Haggis' Porsche was carjacked at gunpoint by two young thieves after he and his then-wife were leaving a video store.

Years later, the encounter still stuck in his head, Haggis awoke in the middle of the night and wrote until dawn, creating a group of characters all linked to the incident. In the film, the carjacking victims are a district attorney and his wife, played by Fraser and Bullock, the Porsche replaced by a Lincoln Navigator.

``I didn't sit down and try to write something profound about racism or intolerance,'' he says. ``I just kept thinking about the kids that jacked my car. Who were they? What did they do when they weren't stealing cars? They were all things that had been troubling me, which is usually what I write about - things I can't explain.''

It took Haggis years to establish himself in television - his first produced script was an episode of The Love Boat. He also wrote for Diff'rent Strokes and The Facts of Life. ``I was a really bad writer for a long time,'' he says. The first script he took pride in was for thirtysomething. After Marshall Herskovitz, the show's co-creator, read the script, he asked Haggis, ``What's it about? What are you writing about from your life that has some meaning?''

Haggis remembers thinking, ``Oh, you're supposed to do that?''

He began creating shows that had substance, although the ones he cared about the most rarely lasted more than a season. The only show he was involved with that became a big hit was Walker, Texas Ranger.

Haggis originally pitched Crash to CBS as a TV series. When CBS passed, Haggis gave it to HBO, which passed, too. Unable to let go, Haggis worked with Moresco, a writer friend, transforming it into a film script. In 2002, an agent got the script to Bob Yari, who was financing independent films. When producer Cathy Schulman came to Yari's company, she became the script's champion.

Haggis' TV credentials meant little in the film world. ``It was a negative,'' he admits. ``It would've been easier if I'd had no track record at all.''

His big break was getting the script to Cheadle, who took the part of a police detective. ``Don gave me status as a director,'' Haggis recalls. ``People would say, `If Don's in it, he must trust this guy.'''

Not everyone has been enamored by Haggis' dire portrait of post-Rodney King Los Angeles. When the film debuted at the Toronto Film Festival last fall, Variety's Todd McCarthy said it ``seems to promote an ideology of victimhood, and shoves race-based thinking to the fore of every human exchange.''

Haggis defends the film's ethnic acrimony, saying: ``We've all segregated ourselves in this city, not just whites but blacks, Koreans and everyone who walls themselves off in their own communities. To me, it's as much about xenophobia as about race. But I'm not promoting victimhood. These are people who, for good or ill, make decisions they have to live with.''

Even though Haggis is outspoken about his lifelong involvement with progressive politics, he sees himself as a dramatist, not a polemicist.

He jokes that his brief moment in the spotlight will fade fast enough. ``I may be hot now, but don't worry, I'll be cool by June.''

He wants to tell stories that not only challenge an audience but challenge himself. ``I love presenting a character we think we all know - a stereotype - and then twisting it around till you're not sure what you really know any more, who's good and who's bad. It's always more interesting to write about something that you don't have the answers for.''