Ordinary Men. A great book about a bunch of ordinary men (50 year old police reservists, from Hamburg, of different socioeconomic classes and political leanings) and the atrocities they committed during WW2 in Poland ( mostly against Jews), why, and how they coped with it. There are some fascinating pieces of information there ( post-war interviews with the men form a big part of the narrative establishing what happened), and it really reinforced some of my already established opinions on "bad people", the Nazis, etc. There was nothing unique about them and such terrible things can happen again, which is why it's so important to teach and remember history - if you don't know how the Nazis convinced millions to do unspeakable things, you can more easily fall in the same trap.