I started watching this at night, because I couldn't sleep. That wasn't such a good idea. First of all, I couldn't stop watching as the impending drama is palpable and you can't look away, you have to watch it unravel. Second of all, that was terrifying. The movie begins by throwing doubt on the father-mother relationship, you don't know who's right or wrong even if the father/ex-husband feels like a beast in hiding. It's subtle, but he seems dangerous, his eyes, mostly, are very cold and his stature is impressive. But the real feat of the movie is its distilled anguish, it's slow, and it feels some scenes aren't useful to the movie but they actually build up until its gripping finale. Anyway, you should watch it, it's masterful and a faithful depiction of the dramas you read in newspaper.
Review of Custody
