Viggo Mortensen is everything you'd want and expect him to be: shaggy-haired handsome, passionate, thoughtful, and smart. The actor-writer-poet-painter and jazz musician pretty much seems to be the Renaissance man in real life that he is on paper. Only then it happens.

Mortensen, already wearing a navy Montreal Canadiens jersey over worn jeans, pulls a Canadiens knit cap onto his head. Like that he's transformed, not just into everyman but into every hockey fan. He may be an acting chameleon - crazy-sexy in one movie, scary-dangerous the next, then slumped-over broken - but there is nothing pretend about this performance. Aragorn from The Lord of the Rings trilogy talks trash, and today his target is the Boston Bruins, who play his team next month in Montreal.

"Good luck, Boston," Mortensen says, sounding utterly insincere. "It's Montreal's 100th anniversary celebration on Dec. 4. You're going to be at the Bell Centre. And I think it's going to be a very difficult night for Boston."

For a moment, Mortensen could be any guy anywhere. It's a role he's familiar with these days. In his new movie, The Road, faithfully adapted from Cormac McCarthy's heartbreaking but ultimately life-affirming 2006 novel, Mortensen plays a nameless character identified only as The Man. Along with The Boy, his son, he is trying to survive a post-apocalyptic world.

It was not an easy read, and The Road, opening Wednesday, is not easy viewing. Mortensen, 51, said he knew going in what he was going to have to put into the shoot, and what it was going to take out of him. Almost every day of filming was so bleak that on the final day, when Mortensen stepped into the natural sunlight, he blinked hard and could not believe the brightness. He says he had lost about 30 pounds and almost all sense of what the regular world, what happiness, was like.

"I knew going in that was the deal if I wanted to do it correctly," Mortensen says. "Am I up to carrying the emotional burden or going to that place I'm going to need to go to be honest about this story?''

With just him and newcomer Kodi Smit-McPhee, who plays his son, carrying most of the film, there was no faking it, Mortensen says. That's why the casting of Smit-McPhee, 13, was as much a wonder as it was a fluke. His resemblance to Charlize Theron, who plays the mother who cannot accept the destruction of life as the family knew it, is eerie. Throw on her coat and cap, as her son does, and it's impossible to look at him without thinking of her. They even have a similar accent. Mortensen couldn't be more complimentary.

"It was just the two of us, and you were either going to believe this emotional journey or you weren't," Mortensen says. "But [Smit-McPhee] was willing and able to go there. And I had his back and he had mine and you can see that on screen. . . . There's real affection and commitment."

And amid all that grimness, he adds, "we did have a laugh now and then," thanks to the pranks pulled by Smit-McPhee.

There were also insects. Lots and lots of insects. Shot mostly in and around Pittsburgh, where the cast and crew cheered the slanting rains and lousy weather that added authenticity, The Road taught Mortensen about survival at its most basic (he was already a skilled outdoorsman and horseman). So when he and Smit-McPhee found a Mexican grocery store that had insects for eating, some with vinegar, some peppery, most of them fried, they had a bug buffet. Then they told the director they wanted to eat them on film. And so they did.

Director John Hillcoat says he was not at all surprised how game Mortensen was. His name came up early in casting, and Hillcoat immediately thought of The Grapes of Wrath and the faces of Okie men worn down by impossible times.

"The physical endurance and the physicality and the huge emotional stuff that he has to carry on his face - there's so much he can't share with the boy," Hillcoat says. "There is something about Viggo's face. . . . And he's got the physicality there that reminds me of people trying to get to California in the Dust Bowl. . . . I also knew he had this fearless dedication to the roles he takes on."

Those roles date several decades, and include parts in the pastel pastiche that was Miami Vice in the early 1980s, and movies such as G. I. Jane, A Perfect Murder - in which he played an artist and his own bold paintings played the art - A Walk on the Moon, [/i]A History of Violence[/i], Eastern Promises, and, obviously, The Lord of the Rings trilogy. Still, mention his name to many moviegoers and . . . blank stare. The face, however, is almost instantly recognizable, hockey cap or no.

The face has got a lot of selling to do, and Mortensen knows that, too. The Road was an international bestseller, but a difficult book is different when translated to screen, especially so faithfully. There is no respite from the reality that people are bag-of-bones hungry and some humans are now hunting humans.

The Boy's fate, and The Man's ability to teach him enough in time about the kindness and humanity that has slipped away, are in question until the end, and perhaps even after. But what's clear throughout is that Mortensen not only wants Smit-McPhee's character to survive but to grow into a good man despite being surrounded by such ugliness.

Mortensen, whose own son is 22, says he could relate to his character's impulse. In fact, during his only conversation with McCarthy (the author also of No Country for Old Men), they spent the entire time talking about children and caring for them. Mortensen says he never got to address any of his questions, which had turned his copy of The Road into one large yellow Post-It. He also says he realized it didn't matter. He finally understood that the central theme was human bonds, not necessarily blood relations, and that was what has fueled the book's worldwide appeal.

Mortensen is himself a citizen of the world, and not in the clichéd sense. As a child born to an American mother and Danish father, he lived in New York, Denmark, Argentina, and Venezuela. (He's actually a Viggo junior.) Casual conversation takes him around the globe. He's not overtly political, but he's got opinions. He's earnest without being exhausting.

Despite being known for his intense immersion in his roles - he wrote an entire back story for this character - he appears to have washed himself clean of The Man, helped along by the long summer after filming that he spent gardening and surrounded by his visiting Danish clan. But the film's notion of life and death and who matters has stayed with him, showing up in his own photographs and writing.

"It's about a leap of faith and trusting people," Mortensen says. "There's no sure thing . . . but there's a chance. Things might seem really bad, but you never know. It's like somebody once asked me what advice would you give a new actor, how do you get to be a good actor? Stick around. You never know."