In the throes of the Toronto International Film Festival (which ends today), Geoffrey Rush sat on the edge of a couch in a hotel room and began celebrating the fine work of his fellow performers.

Naturally, the Australian actor had admiration for Cate Blanchett, his Elizabeth: The Golden Age co-star. But the night before, he'd attended the gala premiere of Canadian director David Cronenberg's Eastern Promises, opening Friday.

"Viggo Mortensen gives a great screen performance," said Rush, using Mortensen's turn as a Russian mobster as an example of the endangered power of screen acting.

"He's completely inside his imaginative world, creating a character using invisible technique. There's a great kind of personal stamp that's idiosyncratic for the character. He explores extreme parameters within the character on his own terms and therefore creates something entertaining and thrilling for an audience to get involved with on their own imaginative level."

It was unsolicited praise from a gifted performer - and deserved.

In Eastern Promises, Mortensen is Nikolai, chauffeur, go-to guy, friend to Kirill (Vincent Cassel), the son of restaurateur and crime boss Seymon. If Kirill has moments when he seems to be channelling the weaknesses of Fredo Corleone, Nikolai is Tom Hagen with muscle and all the tattoos of a one-time prisoner of the former Soviet Union penal system.

There are actors whose performances come as light emanating from the screen. Then there's Mortensen. His effect is gravitational. It draws you closer, inward.

Hard of jaw, cleft of chin, Mortensen has done deep-tissue work in G.I. Jane, The Indian Runner and Portrait of a Lady. He was the man who would be King Aragorn in the Lord of the Rings trilogy. A few years back, sitting in a Dallas ballroom doing solo press for Hidalgo, he didn't seem supremely uncomfortable with the tasks of leading man. Indeed, he approached what felt then like his big shot at studio stardom with a sincere ethic. But it was also clear his heart and curious mind were in the craft.

In 2005's A History of Violence, in which he plays a former mob killer who'd found a new, authentically tender life in a small town, Mortensen's intense determination found a champion in Cronenberg.

And, like Martin Scorsese with Robert DeNiro (and more recently Leonardo DiCaprio) and Quentin Tarantino with Uma Thurman, Cronenberg has found a match and a muse in Mortensen.

"When we did History of Violence," Mortensen said on the phone before travelling to Toronto, "we didn't know each other. We talked a lot beforehand. We didn't know each other as well, but by the time we started shooting History of Violence, we already had a very good shorthand. I felt really safe in his hands. He was someone I wanted to go the extra mile for. I just knew we were on the same wavelength. It was exhilarating."

One can take Cronenberg's work for granted, Mortensen said, "like you do a good score.

"Then, when you watch it again, take it apart, and realize how intricate the construction is."

Their latest collaboration, Mortensen believes, is every bit as challenging and interesting as their first was.

It is - and then some.

There are few movie titles that could be as tonally at odds with A History of Violence as Eastern Promises. Cronenberg has joked that the title of the film (written by Dirty Pretty Things scribe Steve Knight) sounds like it could be a perfume.

But going deep into London's Russian mob doesn't bode well for the kinder, gentler moniker.

At the start of Eastern Promises, Naomi Watts' midwife character has watched a pregnant Russian immigrant die.

The woman's baby survives. So too do the woman's words, in an incriminating journal about her abused life.

We have already witnessed an even more dramatic death in a barber shop. It is the sort of demise that reminds audiences that Cronenberg won't allow us to forget the viscera that comes with brutality.

That Eastern Promises could carry the disclaimer "no guns were used in the making of this movie" doesn't spare a one of us.

A scene in a Russian bathhouse with Nikolai fighting so believably for his life lurches toward the precipice of the pure primal. And you're likely to be hearing about the scene for some time to come: Mortensen played it in the raw.

"It's not gratuitous. If people talk about it out of context it may seem so," the actor said of the harrowing scene. "It's a real work of nature is what I'd say about that sequence, and absolutely necessary. And after that scene everything has changed: the audience, my character has new information."

It was Mortensen who decided the truth of story and the logistics of a steamroom demanded Nikolai be nude. "I don't know whether it would have felt as right doing it for another director I didn't feel that connection with," he said.

"Viggo's an artist," said a movie exec and Mortensen fan during the Toronto fest. The way he said it underlined "artist."

Indeed, Mortensen takes photographs. He writes poems. He paints. At the premiere, he reportedly handed out CDs.

He even runs a small press called Perceval.

If you go to the website (www.percevalpress.com), you'll see some of those wares. You can also browse the "We Recommend" section, which Mortensen puts together on the fly.

The morning I go to the elegant site, the recommendations are a far-ranging clue to Mortensen's broad interest: a slew of political-cultural critiques, the movie The 11th Hour and a CD by New Zealand's Hinemoana Baker.

"It's a hodgepodge," he admitted. "Some days you'll call it up and it will be all articles about the U.S. government or nature. Or it could be Russian poems. It could be anything."