Their history of violence - David Cronenberg put Viggo Mortensen through the wringer once. Now the actor's back for more.

"Well, it's obvious," Mortensen told him, "I have to play this naked."

Boy does he. And Cronenberg captures every clammy square inch of Mortensen's well-toned flesh as it's pummeled and slashed and slammed into the unforgiving bathhouse tiles by two clothed real-life professional fighters, turning an otherwise excruciating four minutes of film into a quintessential Cronenberg statement.

"Eastern Promises," a Focus Features release opening Friday in L.A. and in 1,500 theaters nationwide on Sept. 21, explores the fine line between fragility and brutality, humanity and horror in the lives of three Londoners: Russian mob driver and sometime "fixer" Nikolai Luzhin (Mortensen); London midwife Anna Khitrova (Naomi Watts), who is striving to unite an orphaned baby with her Russian family; and mob boss Semyon (Armin Mueller-Stahl), who hides his sex slavery trade behind the guise of a grandfatherly restaurateur.

The film is Cronenberg's first collaboration with Mortensen since their 2005 Oscar-nominated "A History of Violence," a critical and commercial hit that fans of Cronenberg's previous work -- "Dead Ringers," "Naked Lunch" and "The Fly," among them -- considered surprisingly accessible. It's also a tough act to follow.

So far, reviews have been strong, praising Mortensen's complete immersion in the role -- adapting his body language and perfecting the accent -- calling the performance "brilliant," and even "Oscar-caliber." Indeed, Focus Features' decision to open the film in mid-September, traditionally a dead period for serious films, could give "Eastern Promises" a jump on the glut of performance-heavy fare coming in October.

And despite its disturbing subject matter and memorable fight scene, the film could prove even more commercial than "A History of Violence." It has just three scenes of violence. But the director gives each throat-slice, each blood pool a natural, three-dimensional effect.

"I have a very existential approach to the human body," Cronenberg said. "I take bodies seriously, [as if] I'm actually photographing the essence of this person."