The author of the authoritative but controversial German National Socialism and the Quest for Nuclear Power (not reviewed) here answers his critics and expands on several themes having to do with Nazism and science. The book's opening essays deal with Nazi physicist and Nobel laureate Johannes Stark, who tried to banish Einsteinian physics from Germany; with Werner Heisenberg, the brilliant young theorist who had to defend himself against Nazi charges of being a White Jew''; and with the Nazis' political subordination of the Prussian Academy of Sciences. In the concluding chapters, Walker analyzes theFarm Hall reports,'' secretly recorded and transcribed conversations among leading German scientists held captive at a British estate right after the war. The author's observations are sensitive and penetrating, and for the most part he defends himself ably against critics who have accused him of overstating the competence of nuclear physicists who did bomb-related work for Hitler and of being too forgiving of their moral failures. Walker's efforts are marred, however, by a stubborn streak: He greatly understates the gravity of the errors Heisenberg made at Farm Hall in his first critical-mass calculations, and he is much too easy on Heisenberg's friend and collaborator Carl Friedrich von WeizsNcker, who argued that the German scientists had ``withheld'' from Hitler a bomb they could have built. The book also suffers sometimes from inexact diction, which has made Walker vulnerable to gratuitous criticism before and will continue to give rise to misunderstandings. As the author himself points out, the debates over the Nazi atomic bomb have persisted beyond all reason, considering that they came nowhere near building one. But for the true Nazi nuclear- physics junkie, this latest work will provide a high-octane fix."