A book possibly unique in what it contains.
The author, a Jewish American, went to Germany shortly after World War II, found a town, and befriended ten Nazis who lived there. Hiding that he was a Jew, and that he had other sources of information about them, he yet honestly told them that in the interests of understanding, he wanted to know about how they became Nazis and lived as Nazis. He also includes some from other sources of information, talking to other, German professors and the like. But the core ten group are mostly of men too unreflective to have ever come forth with this sort of information on their own.
They were all "little men." At one extreme, one had been justly convicted of having participiated in a synagogue burning on Kristallnacht. At the other, a teacher had joined to help hide his Social Democrat past, which meant certainly losing his job if it were found out. In between, they included a man who joined because the Nazis were the first political party, ever, to have held a meeting in his farming village, and another who joined to protect his job when his boss did -- not knowing that his boss was an ardent anti-Nazi who had joined to protect himself from his boss, an ardent Nazi, and who covertly tried to get him fired, assuming he was sincere, only the boss's boss protected him.
The teacher explained there were five teachers who didn't join the party. Three were religiously motivated. One never joined anything. And one, who ardently poured the Nazi doctrine into his biology classes
Full of little details about this and that in life. Their actual interactions with Jews in real life, and what they knew, for a certainty about what was happening. The story of a judge who was consumed with guilt for his failure to convict a Jew for a crime while thinking him innocent -- out of jail, the Jew fell into the hands of the Party for a racial offense. (The detainment of the Japanese in the United States came up often.) The unwillingness to blame Hitler rather than Himmler, or Goebbels, or Bormann.
The difficulty of teaching under the vague guidelines -- among Shakespeare's plays Macbeth and (of course) The Merchant of Venice were recommended, but none of the rest forbidden, not even Hamlet for its flabbiness of spirit. (He resorted to A Midsummer's Night Dream so he could talk about Mendelssohn's music.) On the other hand, in math classes, the teachers were given the problems they were to set. Such as graphing by using population growth rates, and adding the question about what dangers the Germans face as a consequence.
The last section where he leaves off the interviews and intimate discussions seems to me to be the weakest. Still, the earlier sections are vital.