During the war dissenting priests and other Christian leaders were sent to the Pfarrerblock, the Priest Block, in the Dachau Concentration Camp. Henri Kremer, a Catholic priest from Luxemburg who has been locked in the camp after aiding the French resistance, is sent home for a nine-day holiday. If something sounds too good to be true it usually is. After two days he's invited to meet the German officer Untersturmführer Gebhardt and he's given a job: he has to speak to the Bishop of Luxemburg and convince him to make a statement supporting Hitler and the Third Reich.
The rest of the film is fascinating. After reading the last paragraph it might seem like a simple case of a religious man having to stand up for what he believes in. Not at all. Gebhardt has received theological training and decided only two days before his ordination to priesthood that he could best serve God if he joined the SS. The two men spend days in theological arguments, and whatever seemed black and white at first becomes a murky grey.
The film is slow, with very little action, but it's intense and thought-provoking. I highly recommend it to people, religious or not, who want to watch a film that will make them want to sit and discuss it for weeks.