On several trips to Los Alamos over the years plus five years spent working at the University of Chicago right across from where the first sustained nuclear took place, I've gotten a pretty good idea of what went into the development of the atomic bomb -- or at least I thought I had until I read this book.
What was missing from the picture for me was the absolutely huge effort that went into producing enough uranium 235 and plutonium for the two bombs that were ultimately designed at Los Alamos. And that, I learned, took place at labs and immense purpose-built plants around the country, including at Oak Ridge, TN and Hanford, WA. I vaguely knew that Oak Ridge was involved in the Manhattan Project, but in the detailed description of the scope of the project in this book, I realized that Los Alamos was not the only "secret city" or "atomic city" during the final years of the wear.
The Manhattan Project is in large part an ode to the usually unsung heroes of industry and engineering as well as the military project managers -- not just to the scientific minds behind the development of the bomb. Front and center is Brigadier General Leslie R. Groves, but there's a cast of scores of people who had a hand in developing the techniques needed to separate out the necessary uranium 235 and plutonium, come up with ways to trigger the bomb, designed the various plants that manufactured needed components, and other vital tasks. This is definitely a "nuts and bolts" or "the way things work" account of how the bomb was built, with almost no stone unturned in describing each aspect of design -- and the countless obstacles and setbacks met along the way.
The reason I don't rate the book higher, however, is that there is a certain predictability in the descriptions of the key figures involved -- a faint (radioactive?) glow of hagiograpy, if you will. Some of the narrative gets bogged down. While the author made it abundantly clear that almost insurmountable obstacles were overcome, reading about each and every one of them got a bit tiresome. The book straddled two purposes -- a factual narrative and a "you are there" suspense tale, but the latter suffered from the former (plus, of course, we all know how the tale ended).