When this movie was released in 1974, it created a huge scandal and strong controversies because it was the first movie about the second world war to introduce a collaborator and not a resistant as a main character. Louis Malle was surely affected by these controversies and he decided to escape into the dream and imagination in his next film: the odd and underrated "Black Moon". So the main character here, Lucien Lacombe, is a member of the German police but he didn't choose this situation because he is anti-semitic or he's fond of Nazi thesis. It's simply because he is a victim of his naivety and of his foolishness and he's easy to persuade. Several times in the movie, you are under the impression that he doesn't know what he's doing or saying (for example, when he's drinking champagne with Albert Horn, a Jew tailor and his daughter France). On the other hand, the stroke is responsible of Lucien's entrance in the collaboration: the school teacher doesn't want him to enter the Resistance because he's too young, he had a flat tyre.... Moreover, the action takes place in june 1944 and it's not the right era: it's nearly the end of the war I also noticed that the collaborators were initiating him into several activities (at one moment, one of them is learning him to fire with a browning) without taking care of his opinion. With all these happenings, Lucien's behaviour is changing: he becomes rough, haughty, scornful, takes advantage of his wealthy life and committs a few errors ( Horn is under arrest due to him and he didn't want it to happen). At the end, Pierre Blaise provides a great calibre in his main rôle and thanks to this, the film is strong, powerful and remain one of Malle's best films.
Note: the movie was inspired by a real fact: during the second world war in France, a young collaborator had arrested and killed numerous resistants.