Regardless of what the ads might suggest, "Eastern Promises" doesn't rest mainly on Mortensen's he-man shoulders. Naomi Watts, as Anna, a midwife in a London hospital who delivers the baby girl of an unidentified heroin addict, may well get more screen time than Mortensen does. When the 14 year-old junkie dies during the birth, Anna digs through the girl's ratty belongings and finds a diary written in Russian. She takes it home with her, hoping that she’ll be able to locate some relatives who can give the infant a chance at a decent life.

Anna’s aunt and consistently intoxicated Russian uncle are split on what should be done with the diary. But a business card stuck between its pages eventually leads Anna to an upscale Russian restaurant owned by a kindly old man named Semyon (Armin Mueller-Stahl), who the audience soon realizes is the head of an organized crime family. Anna has made a copy of the diary, and Semyon offers to translate it, although he oddly seems to covet the original. Hoping to avoid getting her ornery uncle involved, Anna takes Semyon up on the offer, never suspecting that he's an industrial-strength sleaze, and that his no-goodness encompasses such old standbys as forced prostitution, rape, and drugs. But he makes terrific borscht.

Mortensen is little-seen during all of this. He plays Semyon’s driver, a nattily-dressed, perfectly-coiffed brute named Nikolai. After that early scene where Nikolai casually relieves a murdered associate of any identifiable body parts (at least Cronenberg doesn't show him yanking out the corpse’s teeth, which is the announced next step) Mortensen practically becomes a supporting player for an extended period.

Far too much time is wasted on uninteresting, not entirely convincing scenes between Anna and her uncle, and Watts, although she’s perfectly competent, simply doesn’t command the screen the way Mortensen does. Few actors do, and you keep waiting for him to return. The bemused expression Nikolai wears while being ordered around by Semyon’s dim-witted son (Vincent Cassel, as the Fredo of the family) says more about the character in a matter of seconds than Watts can manage in five minutes of huffing and puffing about that innocent little baby. And the promised forbidden romance between Nikolai and Anna never really gets off the ground. It barely even flaps its wings.

That said, Mortensen is superb. If he wanted to, this guy could be typecast in CGI-bloated sword-and-sorcery epics for the rest of his life. But he obviously has years of great, varied work ahead of him. He possesses an uncanny ability (just as Robert De Niro did, before he got smug and quit caring) to completely disappear into each new role, and he can find the heart beating in even the most wretched character- Nikolai, believe it or not, is a pretty funny guy. I watched “A History of Violence” on dvd the night before viewing “Eastern Promises,” and it’s hard to believe that the same man appears in both movies...that is, until he starts busting up people’s faces and snapping their arms like kindling.

Everyone is rightfully talking about the scene in “Eastern Promises” where Nikolai, sitting tattooed and buck naked in a steam bath, is suddenly entangled in a vicious brawl with a couple of box cutter-wielding Chechen hit men. But if you’re thinking this is a golden opportunity to see Viggo swinging some pipe in the open air, be warned. The guy’s naked, all right, but the scene is goddamned brutal. That's about the most accurate way to describe it. Suffice it to say that Russian thugs are not familiar with the Marquis of Queensbury.

Cronenberg, of course, is a superb visual stylist who can cut a series of shots together as well as anyone this side of Steven Spielberg. And that’s saying something. But he amps the ugliness considerably when he chooses to let the steam bath scene play out with no distracting music. All you hear is grunting, flesh being slashed, screaming, bones cracking, and, finally, gurgling. Then he tops it all off when Mortensen, whose torso is smeared with his and everybody else's blood, does a number on one guy’s eyeball that would make Luis Bunuel and Salvador Dali wretch. It’s as brilliantly constructed as any sequence I’ve ever had to turn away from.

“Eastern Promises” is definitely made for grown-ups, and Mortensen’s complex performance deserves to be seen by as many people as possible. Cronenberg, however, seems to have lost his pulpy sense of rhythm with this one. The first half of the story is so belabored, the final act seems shockingly incomplete, and a surprise revelation concerning Nikolai comes way too late to be properly examined. Cutting 15 minutes at the beginning and adding 20 at the end might have given it more balance, but that still wouldn't make up for some of the lapses in believability.

Nevertheless, you'd be wise to keep an eye on Cronenberg and Mortensen; they're the closest thing we currently have to mid-70s Scorsese and De Niro, and I'm including Scorsese and that babyfaced kid from "Titanic." They feed off one another's perverse energy, and they're bound to get things right again at some point in the future. Even this partial failure has moments of genuine, unnerving elegance.

- Paul Tatara