David Cronenberg, the king of so-called Body Horror, seems an unlikely choice to helm this adaptation of Patrick McGrath's acclaimed - and very London-centric - novel.

But after watching Spider, you wonder if anyone else really could have brought this story to the big screen.

Ralph Fiennes stars as Dennis Cleg, nicknamed Spider by his late mother, a shambling shell of a man who arrives at Lynne Redgrave's halfway house after being institutionalised following a childhood incident involving his mother (Miranda Richardson).

He starts to revisit his childhood haunts, trying to solve the mystery of his past - a course that leads to a downward spiral into insanity.

This is the polar opposite of the usual Hollywood myth of mental illness, depicted in such high-gloss trash as A Beautiful Mind (a film whose best picture Oscar will come back to haunt the Academy in years to come).

Fiennes' performance is little short of amazing - this is a character you really feel is teetering on the edge of sanity.

His schizophrenia is conveyed through frowning and mumbling, with only a single line of coherent dialogue - there's none of the showboating of Russell Crowe here.

The effect of having Miranda Richardson play multiple roles and having characters change appearance is both disarming and unsettling at first - placing the audience in Cleg's position as he struggles with his schizophrenia.

Fiennes also appears in the flashback scenes, lurking outside windows or in corners of his childhood home, even sitting in his parents' local pub.

You soon realise that, although some of the flashbacks are real, others are distorted by Cleg's illness or are total figments of his imagination.

Certainly, the film expects the viewer to do some of the work, but the rewards are ample.

After the playfulness of 1998's Existenz, Spider sees Cronenberg producing what should be one of the arthouse hits of 2003.

The Canadian director's regular cinematographer, Peter Suschitsky, does sterling work and the film's production design is a masterpiece of drabness, with greens, browns and greys throughout to present an almost claustrophobic and crushing atmosphere.

With the boundaries blurring between reality and illusion, and nothing being what it seems, this is classic Cronenberg - disturbing, uncompromising but ultimately rewarding.

Adrian Zak