In this meticulous, vivid, and grim accounting of the deliberate murder of civilians by Nazi Germany, Kay manages to keep a balance between careful analysis of the evidence and reminders of the horrors of the events he is describing, including individuals’ harrowing recollections of surviving by hiding among dead bodies—often those of their own relatives. The attempt to eliminate the Jewish people stands out because of its scale and animating ideology, but Kay shows how that was only the most extreme manifestation of a wider horror that depended on the dehumanization of victims and the perfection of the means of extermination. In calculating how many people the Nazis killed, he reaches a figure of 13 million during the war years alone, most of whom were murdered through starvation, shooting, or gassing. In addition to the Holocaust against the Jews, Kay describes the Nazi campaigns against people with mental and physical disabilities, the Polish elite and the occupants of Warsaw, the Roma, civilians in Soviet cities, and others unlucky enough to live in Nazi-occupied territory. This was an unparalleled exercise in collective violence, with “hundreds of thousands of mass murderers at large simultaneously.” Kay eschews monocausal explanations, pointing to a combination of Nazi ideology, historical circumstances that encouraged radicalization, and the impunity permitted by war.