Malle tackles the difficult subject of collaboration in the second world war in France without taking a judgemental approach. He illustrates how fate can lead an uneducated and weak French peasant boy to back the wrong horse and collaborate rather than join the resistance. Good performance by the amateur Pierre Blaise (sadly killed soon after this film)as the title character. Warning to animal lovers - several scenes of animals being killed, showing the unsentimental way in which the peasant boy treats death.
Right from the beginning of the film we know just what Lucien is like, a nasty piece of work who takes great enjoyment in killing animals, albeit for eating in the case of one of the rabbits he takes to his mother. He seems to like nobody, including the Jewish girl who he seduces and her father, the tailor whom he tips off to the Germans, thus showing the malicious hatred he feels for the "enemy", although he does gain some redemption in escorting the girl and his mother to Spain, or this may have been because the Germans have been beaten and he's thinking of his own skin. But for all this nastiness the film itself is a masterpiece and Pierre Blaise is brilliant.
This film, which has become a controversial classic in France, gives a unique insight into what things were like in wartime France, while the country was occupied by the Nazis. Lucien Lacombe, in the movie, is a teenager of peasant stock, who comes from a small village. He hesitates between joining the Resistance movement, close to the Communists, or collaborationist circles, and the paramilitary police that works closely with the German authorities, including the Gestapo.
What the film shows, and which shocked people in France so much at the time (and even since), is that some people joined one side or the other out of ideological convictions, but many may have done so due to circumstance and out of opportunism more than anything else. In the movie, things are not clear-cut: there are many grey areas and guilt is not black and white. Having said that, many of the individuals who worked for the so-called French Gestapo (la Carlingue) were indeed gangsters and criminals, who saw the Occupation of France as a golden opportunity to do business. (See here: https://en.wikipedia.org/wiki/Carlingue)
The way that collaborationist circles are portrayed is unforgiving and very realistic: to say that the director was trying to defend Vichy France, as some commentators have done, is clearly absurd and unjustified.
The film is very good. It works from start to finish, with excellent acting, among other things. It has not aged at all, by which I mean the style of the narrative still feels fresh and immediate. Even if you are not particularly interested in period films and in history as such, I strongly recommend this disturbing historical drama.