Egregoros

@kaia
L'affaire des divisions Morituri: https://www.imdb.com/title/tt0139000/
It's sorta "action" though — has such sequences, but it is otherwise slow-paced. It also has loud music at times and people talking loudly, so it's not exactly a "relaxing" movie.

Then there's this movie, also by F.J.Ossang: https://www.imdb.com/title/tt1847577/
AFAIR this one's more "calm".