Detective Dormer (Al Pacino) can’t sleep. He and his partner, Hap Eckhart (Martin Donovan), are LA cops on special assignment to investigate the brutal murder of a teen-age girl in tiny Nightmute Alaska. Dormer may have been brought in for his expertise – eager young Nightmute detective Ellie Burr (Hilary Swank) tells him that she did a case study on one of the crimes he solved when she was in school. But Dormer and Eckhart may have been sent to Alaska to keep them out of the way of an Internal Affairs investigation. They are investigators and subjects of investigation at the same time.

This is just the first of many dualities and counterpoints in a complex, thoughtful thriller directed by Christopher Nolan, who gave us last year’s breakthrough hit about an amnesiac searching for his wife’s killer, Memento. Like that movie, “Insomnia” has an impaired main character. We cannot always trust what we see through his eyes.

Neither can he. Shortly after arriving in Nightmute, he asks to be taken to the local high school so that he can interview the dead girl’s boyfriend. The local detectives glance at each other and explain that it is 10 o’clock. Dormer looks out the window and says, “So what?” But it is 10 PM in a time of year when it is light all night long. Images of light and darkness haunt Dormer as he tries to escape the light so he can get some sleep and as he is forced to confront a darkness within himself that draws him both to the killers and to their eradication. It turns out that he and the killer will have a connection that, like the midnight sun, will keep him awake.

Nolan uses everything — the huge frozen vistas, the disorientation of perpetual sunlight, the fog that surrounds their first glimpse of the killer, the names (Dormer is “to sleep” in French, Ellie Burr is a detective whose dedication is a constant irritant). Dormer’s lack of sleep both deconstructs and constructs him. He enters a surreal state in which he is both more and less able to rely on his judgment.

Pacino, Swank, Donovan, and Maura Tierney as a sympathetic hotel proprietor are all first-rate. The movie’s weakest point is Robin Williams in the under-written role of the killer.

Parents should know that the movie has brief but grisly violence, a nude corpse, some creepy sound effects, and some very strong language. There are tense scenes and characters are shot and killed. Characters drink and smoke.

Families who see this movie should talk about the moral compromises Dormer makes and the ways in which people have to balance the ends and the means. What will Ellie do next? Why? Why is the town named “Nightmute?” What do you think about the girl who was killed?

Families who enjoy this movie will also enjoy No Way to Treat a Lady, Strangers on a Train and Memento.