I'm working on an essay on "Why Germany Didn't Get the Bomb," so I just finished "Heisenberg's War" by Thomas Powers. It's brilliantly researched and covers an enormous swath of prewar and WWII science and intelligence. His basic premise is that Werner Heisenberg, a Nobel laureate physicist and head of Germany's effort to develop nuclear weapons, led the project "into a broom closet" to keep Hitler from getting his ultimate weapon.

A contrary view is taken by a book I read earlier, "Heisenberg and the Nazi Atomic Bomb - A Study in German Culture," by Paul Lawrence Rose, a professor at Penn State. He believes the Germans would have developed an atomic bomb if they knew how--but they didn't. He believes Heisenberg and his colleagues put out the story that they knew how but didn't want Hitler to get it to preserve the "honor" of German science in the face of the American triumph--and also to polish Heisenberg's image from the tarnish it got by association with the Nazis.

They're both teriffic (but challenging) reads. My conclusion falls somewhere between the two.