Skjoldbjaerg's film centers on a Swedish cop (Stellan Skarsgård) with a slightly seamy reputation who is sent to a town in northern Norway to investigate the fatal beating of a high-school girl. The sun never sets in summer there, and the cop's skills and mental stability are compromised by his inability to sleep in the constant daylight.
Here, Al Pacino is Los Angeles cop Will Dormer, on loan with his partner, Hap Eckhart (Martin Donovan), from the LAPD to the small town of Nightmute, Alaska, which doesn't have adequate resources or experience to investigate a mysterious killing (again of a high-school girl). Dormer is a legendary homicide detective -- so famous that green, enthusiastic local cop Ellie Burr (Hilary Swank) has studied his cases and can remember things he's said and written that Dormer himself has long forgotten.
Early in the investigation, a stakeout goes horribly awry: The killer, Finch (Robin Williams, not visible until more than halfway through the film), escapes. In a chase through the fogbound surroundings, Dormer accidentally shoots and kills Hap.
Dormer knows that no one will believe it was an accident; he is under investigation in a Ramparts-like scandal back in L.A., and he knows that Hap has cut a plea-bargain deal in return for testifying against Dormer. So our hero improvises, claiming that it was the killer who shot Hap. Of course, no one has any reason to doubt him except the killer himself, who was close enough to see what really happened. Soon, Finch contacts Dormer to blackmail him, and a cat-and-mouse struggle over the physical evidence is complicated by Dormer's sleep-deprived psyche.
For the first half of the movie, those who have seen the Norwegian version may be surprised at how closely Nolan's direction and Hillary Seitz's screenplay cleave to many details of Skjoldbjaerg's original. But the internal-affairs investigation that gives Dormer a motive for killing Hap is a new element -- one that shifts the story's moral and psychological concerns. In the original, the cop's flaws mirror those of the killer precisely: He is shown to be capable of the kind of sexual impulses that led to the murder. In the new version, we see nothing of Dormer's sexual nature.
This change allows Nolan and Seitz to beef up Robin Williams' role and to add a lot of very clever plot reversals during the second half. The psychological fencing between cop and killer is far more interesting here than in the Norwegian film.
There are still problems with Williams' casting. He is irrevocably and unforgettably hyper-funnyman Robin Williams, no matter how muted and controlled is his performance. But the film uses the baggage of his traditionally likable persona to remind us that villains are often unremarkable "nice guys" in their day-to-day lives.
Despite the conventional narrative structure, Nolan fans will recognize his style here -- the nearly subliminal memory flashes, the disorienting intercutting of extreme close-ups and the relentless attachment to the central character's point of view. What Nolan accomplishes in Insomnia that we haven't seen from him before is staging a few horrifyingly effective suspense set pieces likely to stay with you for a long time.