Al Pacino plays yet another cop, this time a veteran cop with a deeply troubling moral complex who has fostered a career of catching serial killers. As soon as Will Dormer (Pacino) arrives in Nightmute, Alaska, to investigate the brutal murder of a teenage girl, we already sense he has seen too much in his work and is exhausted by the sheer banality of the job. In this case, the town itself lends even more exhaustion to Will. You see Nightmute is a town where in the winter, the nights are always bright. Will can't take it, trying to cover his hotel windows with pillows and sheets but it is no use. He fails to sleep and develops insomnia.

Will arrives in this town with his partner, Hap Eckhart (Martin Donovan, who appears to be in a somnolent state), both from the LAPD. Hap is ready to cut a deal back home with the Internal Affairs department over Will's tampering with evidence from prior cases. Will can't take it, and an accident involving Hap while searching for the killer in a rain-drenched, rocky, remote area of Alaska sinksWill even deeper into insomnia and moral dilemnas.

Two people catch on to Will's secrets. One is a smart, quick-learning rookie (Hilary Swank), who learns as much about Will's persona as she does about Will's police training. The other is the killer himself, a second-rate mystery writer, Walter Finch (Robin Williams), who discovers that Hap's accident was no accident at all, and tries to clear himself of the murdered girl by using Will. The twists pile up, Will's insomnia grows out of control, and an innocent person may go to jail instead of Walter. Where will all this lead? Somewhere between the murdered girl's ex-boyfriend and her own best friend (), but that is just the beginning.

"Insomnia" does not submit to the usual cliches found in any typical thriller involving cops and serial killers. The climax also doesn't evolve in a typical fashion. The strength of the film lies in its psychological profiles of its two main characters, Will and Walter. Their cat-and-mouse game is strictly dependent on their personalities and their actions, not motivated by twists generated by the screenwriter to be as superfluous and precious as possible. Also worth mentioning is how the film deals with Will's immoral actions, as we sense that his flaws and screwy ethics could slowly conspire against him. We also begin to feel some measure of pity for Walter, despite his murderous, controlled rage. In short, Williams does not play the killer as a menacing psycho with obvious psychological and mental problems - he plays him as the recluse he is with some measure of restraint. Pacino has a few moments where he hollers but it all comes from his inability to sleep and to deal with his past indiscretions. To say that Pacino and Williams have never been better is to state the obvious - they have given their very best performances by far.

It helps that director Nolan knows how to handle the mood and atmosphere, as well as the actors. From slippery rocks to torn down cabins to floating logs to a stunning opening sequence involving snowy formations along the Alaskan border, "Insomnia" feels as close to a bleak noir thriller as "Fargo" did, using daylight as evocative of danger as the nighttime. In one gripping scene, we see floating logs that keep colliding and preventing the desperate Will from rising to the surface of the water - it is as riveting as scenes like it go.

"Insomnia" is a first-class thriller, expertly shot and staged and acted. Thanks to director Nolan, Pacino, Williams and the rest of the fine cast, this film is as good as mainstream thrillers can get. Rarely do character nuance and observation seem as thrilling as they do here.