Join the wide awake club

Insomnia is a chronic inability to fall asleep; a state of enforced wakefulness that leads to irritability and an inability to concentrate.

In contrast, detection requires full sensory alertness to search for clues in obscure places. Christopher Nolan's impressive third film, after Following and Memento, deploys the idea of an all-pervasive light to befuddle the deductive process and expose the corruption of the soul. Quite literally, it throws light into a moral darkness.

A remake of a 1997 Scandinavian film, Nolan's version is no mere American retread. Together with his screenwriter Hillary Seitz, he has given the raw material of the original a thorough shake-up and relocated the story to Alaska, an alien and terrifying landscape inhabited by only two kinds of people: "Those who were born here and those who came here to escape something."

Into the small, remote Alaskan community of Nightmute, "the halibut fishing capital of the world", fly LA detectives Will Dormer (Al Pacino) and his partner, Hap Eckhart (Martin Donovan). They have been sent to investigate a particularly nasty murder. A young girl has been beaten to death and dumped in a landfill site. Dormer establishes his power from the start, insisting on seeing the body and drawing his own conclusions. At first, he comes across like a 21st century Sherlock Holmes, spotting details and clues and making swift and accurate deductions. But there's a hitch: Dormer and his partner are under investigation back in LA by Internal Affairs. When Eckhart states his intention to cut a deal with the IA, Dormer realises he is endangered by implication. His apparently unsullied record holds just one possible chink. The two partners fall out.

Not long afterwards, while tracking the murder suspect through the Alaskan fog, Dormer sees a figure in the mist and shoots. To his consternation, he discovers he has accidentally shot his own partner, who dies believing that Dormer aimed at him deliberately. Aware of the compromising situation in which this puts him, Dormer lies about the direction of the shot, claiming it was the suspect's bullet that struck Eckhart. Even worse, the suspect has witnessed the shooting and starts telephoning Dormer to suggest they cut their own kind of deal. Thus the Faustian pact is sealed and the dramatic dilemma is established.

Dormer's problems are exacerbated when the local rookie detective, Ellie Burr (Hilary Swank), is taken off the murder case to file a report on the shooting. A man whose deductive reasoning is hinged to apparently inconsequential details for which one must be ever alert, Dormer is kept awake by the white nights of the Alaskan summer. Each successive day sees him increasingly tired. He must, perforce, slip up; not just in the hunt for the suspect, with whom he is now inextricably involved, but also over his own cover-up. The relentless light acts like Nature's interrogation. Deprived of sleep, Dormer's (whose very name suggests somnambulism) defences are gradually eroded.

A film of forensic detail that exposes not just a crime but the stained soul, Insomnia maintains its powerful conceit with great assurance and features the best performance by Pacino for years.

WHEN we first see Dormer he seems dwarfed by his partner, Eckhart, who is at least a head taller than him, which sets up all kinds of responses. And once the die is cast, Dormer has to keep one step ahead of the investigators to save himself. The prime suspect - ironically a best-selling author of police procedural potboilers - is played with an authentic chill by Robin Williams, whose customarily benign individualistic-persona is curdled into a kind of sociopathic loner.

Nolan's intelligent reading of the material allows him to create new tensions from old situations; the inevitable chase between cop and villain, with Williams nimbly jumping across the logs floating downriver from a sawmill while Dormer slips and falls into the water only to find he cannot resurface, conveys all the clammy tension of a more traditional cop thriller. And the panic of Dormer's attempts to retrieve a hidden pistol that could link him to the crime before the local cops arrive for the same evidence is ratcheted up in the best Hitchcockian style. Having shown his clever-Dick trickery with Memento, Nolan settles into the straightforward narrative structure of a superior genre film. As such, he is the closest thing we have to America's Steven Soderbergh - an intelligent-director who can raise the stakes in a mainstream genre.

Suffused with images of Catholic guilt - from the Lady Macbethian scenes of a hand attempting to scrub the telltale bloodstain from a shirt cuff to Dormer's confessional moment with the hotel keeper - Nolan's movie also simmers with the nature of film itself. John Boorman called film "painting with light" and here Nolan takes it literally - from the Fargo-ish whiteout of the opening scene to the leaking light from the edges of the vainly taped-up windows of Dormer's bedroom. Light is what makes a movie - and, like film, guilt has to be "exposed".