The real puzzle is, Did Will Dormer (Al Pacino) also commit murder? That is to say, Did he, with malice aforethought, shoot his partner Hap (Martin Donovan), or was it an accident a snap shot in the fog as they were stalking Finch near the scene of his crime?
This turns out to be a complex and interesting matter. And Insomnia turns out to be a worthy successor to director Christopher Nolan's Memento, which was last year's most discussible hit. The new movie does not tell its story backward you're allowed only one gimmick that sensational per career. It is, in fact, a rather conventionally, sometimes almost ploddingly developed narrative.
The two cops are on loan from Los Angeles, sent to tiny Nightmute, Alaska, to help an old pal, the police chief, solve the crime. They are, though, carrying some extra psychological baggage. Will is a great cop but has planted evidence to make his case against a child molester. Hap knows what happened and is going to talk to internal affairs, thus destroying a legendary career. So Will has a motive to kill him. And this is the best part his judgment is clouded by sleep deprivation. It is summertime in this land of the midnight sun, and the perpetual daylight induces in him the malady of the title.
We will never know, and he will never know, whether Hap's death was willful or accidental. Will, of course, concocts a plausible story, blaming the lurking but at that point unidentifiable Finch for the second crime. He also plants exculpatory evidence to support this tale. Meantime, the creepy Finch tries to lure him into a deal: Finch won't talk about what he saw if Will joins him in pinning the original murder on an innocent kid.
What we have here is your basic good-cop-bad-cop story, except that those two characters are wrapped into one, with Pacino giving one of his terrific tormented performances in the role impatient, arrogant and, in the long watches of the night, almost pathetically vulnerable. Williams is also good an entrancing smoothy you can well imagine Will succumbing to. Hilary Swank represents rationality a smart, inexperienced cop who deeply admires Will and can't quite believe the case she begins to develop against him.
Finally, the film represents a triumph of atmosphere over a none-too-mysterious mystery. Which is to say that Nolan remaking a 1997 Norwegian film, adapted by Hillary Seitz makes you feel the end-of-the-earth bleakness of his setting, makes you feel the way it can discombobulate people once they internalize it. Insomnia is not a spectacular moviegoing "memento," but it is thoughtful, quietly disturbing proof of a young director's gift.