Intelligent, frosty character study of a French serial killer of young girls, based on a real case from the 1970s. The super dark anti-hero is played with great subtlety by Guillaume Canet, and the film is very well shot.
But there's a last layer missing that keeps this from going from a very good film to a great one. As much as it's always interesting, and sometimes even heartbreaking, there's a lack of larger theme or context that keeps this confined to being a thriller/character study - if a very intelligent and thoughtful one - and not the rare film that transcends into something even larger.
But it's still very worth seeing as a study of a brilliant but tortured man compelled to horrible violence, and on 2nd viewing I found it a more powerful and emotional experience, catching details and moments I missed the first time around.