Why did the Third Reich, for all its industrial might and technological resources, fail to create a nuclear bomb? That's the central concern of this masterful, wide-angle reckoning by Powers (Thinking about the Next War, 1982, etc.). At the heart of the panoramic narrative is Werner Heisenberg, whose work on quantum mechanics and the so-called uncertainty principle earned him considerable fame during the 1920's. Along with most other world-class physicists, Heisenberg was fascinated by fission's potential. But unlike many colleagues who had emigrated because of Hitler's institutionalized anti-Semitism, he remained in Germany throughout the war. Love of country partially explained this difficult decision, which also involved a desire to preserve and protect Germany's scientific future. At any rate, Heisenberg--who early on had convinced Albert Speer and the Wehrmacht that A-bombs were a mission impossible--``was free to do what he could to guide the German atomic research effort into a broom closet.'' Fellow scientists--in particular, those assigned to the Manhattan Project--were generally reluctant to accept Heisenberg's subsequent apologia. Nor at the time did Allied intelligence believe that he was trying to develop reactors rather than bombs. Powers nonetheless determines that the unwillingness of Heisenberg and other German physicists to put a superweapon at the disposal of a military/police state was indeed a root cause of Hitler's failure to become a charter member of the nuclear club. In reaching this arguably persuasive conclusion, the author provides vivid vignettes on Heisenberg's peers--Hans Bethe, Niels Bohr, Enrico Fermi, Otto Hahn, Robert Oppenheimer, Leo Szilard, etc. Covered as well are the counterespionage campaigns mounted by Anglo-American agents (including baseball player Moe Berg), who at one point seriously considered abducting or assassinating Heisenberg. A comprehensive and resonant overview, notable for its compassionate perspectives on the moral dilemmas faced by men of genius caught up in a global conflict. (Sixteen pages of photographs--not seen.).