The 2002 thriller is based on the 1997 Norwegian movie of the same name, starring Stellan Skarsgård as a detective trying to escape his past in the Arctic.
Still, there’s enough of a difference to appreciate both versions if you want to do a fun double-feature to compare.
The two versions are identical to one another in almost every way except for the fact that Nolan turns up head-games and hallucinations more than his Norwegian counterpart, Erik Skjoldbjaerg.
It might be hard to imagine that Christopher Nolan would take on any project where he wasn’t the one coming up with the premise, but that was the case for his third film, Insomnia starring Al Pacino as an LAPD detective with a checkered past sent to investigate the murder of a teenage girl in an Alaskan fishing village where the sun doesn’t set.