Lifton starts from the premise that understanding how physicians could embrace Nazism's racist ideology and murderous behavior is the most difficult aspect of Nazism to comprehend. Physicians, Lifton notes, played a crucial role in the Nazi drive toward genocide. Thus, the author wants to know how these doctors became killers, how educated, ordinary people allowed themselves to commit barbaric acts. To do this, he examines what he calls ""medicalized killing,"" specifically, how doctors functioned in Auschwitz. In doing so, he analyzes in depth three particular physicians: Ernst B., who seemed to be what passed for compassionate in the world of the camp; Josef Mengele, presented as the archetypal Nazi fanatic; and Eduard Wirths, a model of how a decent man allowed himself to be transformed into a killer. In a concluding section, Lifton presents a psychiatric theory called ""doubling"" which he uses to explain the evil. (Doubling involves an individual forming a second self, more or less autonomous from the first, which becomes the evil part of the self and which therefore allows the decent part to remain guiltless.) Lifton finally suggests the application of such a doubling theory to the post-Nazi age, one pregnant with the possibilities of holocaust and nuclear destruction. Based on 10 years of research and writing, on interviews with Nazi physicians, other Nazis, and survivors, Lifton has written a compelling book, which, while morally sensitive, is admirably unflinching and provocative. We are finally left shaken by the Nazi doctors' moral failure, but with a far clearer understanding of what they did and why they did it. The book is a major contribution to Holocaust study and medical ethics.