TORONTO - Jason Reitman built his young career on the razor-sharp comedy "Thank You For Smoking" and the teen pregnancy smash "Juno." But when the economy tanked while he was writing his latest movie, "Up in the Air," the Oscar-nominated director knew his trademark satiric tone would have to change.

The film, which opens Friday in Toronto, stars George Clooney as Ryan Bingham, a businessman who has embraced a life of almost non-stop travel as he jets from city to city helping companies fire their employees. In nondescript offices across the United States, Bingham offers a few perfunctory words of advice to devastated workers before flying off to his next job.

"When I first started writing this, I wrote the firing scenes as comedic satire, and as (the economy soured), I realized: 'OK, I need to be more authentic here,"' Reitman said during an interview at the Toronto International Film Festival.

He found the genuineness he was looking for in real-life laid-off employees.

In St. Louis and Detroit -- two cities particularly hard hit by the recession -- Reitman's crew took out newspaper ads inviting axed workers to take part in a documentary about job loss.

The director said they received a "staggering" response. They called about 100 people, put 60 on camera and included 25 in the finished film.

Participants were brought into a room where they couldn't see the camera or crew, said Reitman, and were interviewed by a producer about losing their job. After about 10 minutes, they were told they were going to be "fired" on camera and asked to respond they way they did in real life, or the way they wished they had.

"It was really an extraordinary experience for me, because I'm a guy who, for a living, tries to get people to be honest on camera," said Reitman.

"All these people -- the second they would hear that kind of legal document that's used in every firing . . . you would just see their demeanour change.

"They'd just fall in their seats, their eyes would go soft, one girl broke into hives. . . . They would begin very real improv acting where they would say: 'Why did you choose me? There's a hundred people in my department. Why didn't you choose Steve? Is it because of my age? . . . Or: 'How long is my health insurance going to stay on? Is there another job in the company? How could you do this to me?

"They would say these things that were so real and so heartbreaking. It was very hard to shoot and very hard to edit."

Reitman said those interviews influenced the rest of the film.

"Up in the Air" marks a stark departure for the director. While at times laugh-out-loud funny, it's also imbued with an exquisite sense of melancholy and longing, bolstered by a terrific soundtrack featuring the likes of Graham Nash and Elliott Smith.

Clooney, meanwhile, gives perhaps his most vulnerable performance to date, supported by a cast that includes Vera Farmiga ("The Departed," "The Boy in the Striped Pyjamas") as Bingham's fellow road-warrior and love interest, and Anna Kendrick ("Twilight") as his corporate protege.

Still, while "Up in the Air" -- based on a novel by Walter Kirn -- seems remarkably of the moment, Reitman insists he never set out to make a film about the recession.

Instead, he says, the financial crisis ended up providing an apt metaphor for the character of Bingham, who fully embraces hotels, frequent flyer points and living out of a suitcase until he begins to wonder what it all means.

"The reaction I heard most from people I talked to who had lost their jobs is that it leaves them searching for purpose and I think that's a strong metaphor for our main character who . . . is now looking for his purpose," said Reitman.

"This is really a movie about human connection."

While Reitman grew up on the movie sets of his father, legendary Canadian director Ivan Reitman ("Stripes," "Ghostbusters"), his ascent in Hollywood has, in many ways, been meteoric.

The success of "Juno" made him an awards show darling and there's already similar buzz surrounding "Up in the Air."

"'Juno' changed my life," acknowledged Reitman.

"'Juno' gave me the type of creative freedom that usually is not afforded to someone who's only made two films. When you make a movie for $7 million and it goes on to gross $230 million, people offer you a certain amount of confidence whether it's warranted or not.

Still, at just 32, the Montreal-born director seems remarkably grounded, saying he feels fortunate that his privileged background allows him to focus solely on his work.

"I don't worry about getting paid, I don't worry about making a lot of money," he said.

"My only care is to make great films that I will be remembered for. I don't want to establish wealth, I want to establish a career of films that people look fondly upon."

"Up in the Air" opens Friday in Toronto, Dec. 11 in Montreal and Vancouver and goes wider later in the month.