When German soldiers invaded the Polish city of Lodz at the start of World War II, they confined the local Jewish community to a miserable, overcrowded ghetto. Through family connections, a Jewish teenager named Anatol Chari (far left in photo) became a ghetto policeman. Because they were sometimes viewed as collaborators, ghetto policemen who survived the war kept their past a secret. In From Ghetto to Death Camp, Chari reveals that hidden story, describing the policemen's duties-guarding food, rounding up prisoners for transport-and the privileges it brought them. Those privileges ended...