Viggo Mortensen, Naomi Watts, Armin Mueller-Stahl, Vincent Cassel.

Running time: 100 minutes.

. . . .

IN David Cronenberg's last film, A History of Violence, a small-town diner owner played by Viggo Mortensen became a local hero after he knocked senseless two armed robbers. A longforgotten violent past surged out of him . . . a primal instinct tucked away for the sake of family and society. A Darwinian parable, it exposed the savagery buried within all of us. His new film, Eastern Promises, explores a corollary: when unrestrained brutality needs to be civilised. To put it another way, it's a gangster movie, but here the baser instincts of man come face to face with the civilising influence of a woman.

Eastern Promises features a mesmerising performance from Viggo Mortensen as an ambivalent, tattoo-strewn Russian mafioso on high simmer. It is set in the sinister underworld of the vory v zakone (otherwise known as the Russian mafia) in London and is written by Stephen Knight, who gave us a similar story of dodgy dealings in London's immigration underbelly in Stephen Frears' Dirty Pretty Things. But this comes served with the Cronenberg touch . . . an ambiguous mixture of menace and dark humour that seems to wriggle under your skin. You never know when violence is going to pop out. The film opens with a gangster hit in a barber shop: the executioner, inexperienced and not quite able to make a clean kill with a razor, works back and forth across his victim's neck until blood erupts. Like the many swift shots of vodka consumed in the world of the vory v zakone, death here comes quick and you are likely to feel it first in the throat.

The civilising force that confronts this alpha-male arena comes in the angelic form of Naomi Watts. She's good at this kind of thing. In King Kong she was able to tame the great ape with her feminine charms by dancing on a rock. Here, she bends over her motorcycle and the Russian tough guys sharpen up. She plays Anna Khitrova, a London midwife of Russian extraction nursing her own emotional wounds after a miscarriage.

When a 14-year-old Russian girl dies in labour leaving a newborn child and a diary in Russian, she feels compelled to find out what happened. But she needs the diary translated. A phrase leads her to a Russian restaurant called the Trans-Siberian, and the paternal smile of its proprietor Semyon (Armin Mueller-Stahl), his alcoholic and off-balance son Kirill (Vincent Cassel) and their driver/'cleaner' Nikolai (Viggo Mortensen).

What she does not know is that Semyon is a Russian godfather. Front of the house, he serves borscht; at the back, heroin and young girls for sex. German actor Mueller Stahl is a delicious nasty. He twinkles his blue eyes at Anna in sympathy and offers to help translate the diary. It is, of course, in his interest: the translation will explain how he sold the girl to sex slavery, then with his son Kirill raped her and forcibly injected her with heroin.

Outside, Nikolai (Viggo Mortensen) can't resist a conversation with Anna as she straddles her motorbike. He is a formidable presence: he stands impeccable in black shades, sharp suit and slicked back hair. But his body is a maze of tattoos, a gangster's genealogy of time done, crimes committed and tribal affinity. Mortensen turns inside out: in A History of Violence he was domestic and paternal, slipping into violence; here, he's a fizzing concoction of dangerous elements. Yet Anna intuits something else, a streak of civility. More than Nikolai's soft side is going to be exposed though. There is an extraordinary scene in a Turkish bathhouse where he is attacked by two knifemen. Mortensen, wearing nothing but his tattoos, is hurled about the room. His skin is flayed with a knife, his dignity carved up, and every tumble on the tiles sounds like dead meat dropped on a slab.

Eastern Promises follows Cronenberg's compulsion to disgust as well as entertain.

There is one scene where Nikolai treats a murdered body, removing it of all identification. The soundtrack fills with the sound of a hairdryer, applied to the freezer-frozen body to defrost a pocket and remove documents, and then the snipping of pliars as we observe intimately the removal of the dead man's fingers. "He was like a brother to me, " smarts Kiril, and you crack up too. Revolusion, black humour and a twilight zone atmosphere regularly share the same space.

But the angry humanism of Stephen Knight's script is always poking through.

He works hard to remind us of the reality of gangsterism and the sex-slave trade. In one horrid scene, we see a young woman being raped, her eyes staring absently into space. Watt's Anna takes on the mantle of this anger, and becomes ever more indignant, burrowing deeper into jeopardy.

The craft is slick, the story blindingly entertaining; yet I was underwhelmed by its conclusion, an odd departure into sentimentality the film did not deserve. It wants to reset the balance a little too comfortably. Still, Cronenberg is proving his immense talent for encasing grand guignol and serio-black comedy within the steel-solid structures of his hybrid drama/thrillers. He is one of a kind.