Just finished The Decalogue: Five. Based on the moral ambiguity of capital punishment, its an engrossing story that is nevertheless extremely difficult to watch because of the subject.
Spoiler Alert: the next paragraph might contain some facts about the movie which you might not want to know if you are planning to see it. Though there is no real mystery about the story, I think the movie's impact is better if you don't know anything about it.
A man almost completely devoid of morals murders another man for no reason at all and is defended in the court by a lawyer who has always been against death penalty. Most of the first two-thirds of the movie lacks much dialogue. You just see these three people (the murderer, the victim and the lawyer) going through with their lives on one day and yet the atmosphere created and the performances keep the viewer engrossed in the proceedings.
This movie made me think that one of the major reasons why these movies make such an impact is the consistently splendid performances by the actors. Its amazing to see such acting in movies that were essentialy meant to be episodes of a TV series.