I've recently seen the 2002 remake with Al Pacino, Robin Williams and Hilary Swank and sought out the original 1997 Norwegian version. And I liked perhaps a little more.
The storyline is very similar and goes something like this: Swedish cop + partner arrives in a northern Norwegian town to investigate the killing of a teenage girl. In the fog and suffering from sleep deprivation he accidentally shoots his partner - but then makes the serious mistake of trying to cover it up. His lies catch up with him as he attempts to frame the girl's boyfriend, there is a final struggle in the killer's hideout, after which the killer drowns.
The Hollywood version has attempted to spice things up a little with a backstory about the lead detective being investigated by Internal Affairs and by having a final shootout. Here, the action and the actors are much more restrained and the film moves more slowly. The acting is excellent throughout. In my view the director attempts much more successfully to show the effects of the 24 hour daylight as the lead character suffers increasingly from lack of sleep.
If you fancy watching a Norwegian language film with subtitles, give this one a go. I liked it very much - in fact I liked both versions. Highly recommended - 4/5 stars - the same as the remake - but I think this original version is the better film.