The lead author in big type: Chris Wallace, the Fox News guy. In fine print underneath: with Mitch Weiss. Hard to say who actually did most of the typing.
But let's ignore that for now. The book concentrates on the "countdown" to the dropping of "Little Boy" on Hiroshima. Starting 116 days before, with the death of Franklin D. Roosevelt and ascension to the Presidency of Harry Truman. Truman is quickly told about the Manhattan Project, the super-secret operation at Los Alamos, Oak Ridge, Hanford, etc. to put together the gadget of then-incredible destructive power.
The book is written for broad audiences, concentrating on a few dozen of the personalities involved. It leans toward telling "good stories" up and down the chain of command: the biggies: Truman, Oppenheimer, Groves; the flight crew: Tibbets and the rest. It also tells the story of Hideko Tamura, a 10-year-old kid in Hiroshima who survived. And many more.
The book also examines the iffy ethics in visiting mass destruction on a city with a lot of civilian deaths. (It's hard for us moderns to remember that intentionally inflicting civilian casualties was considered a crime.) I'm probably a little biased: in 1945, six years before I was born, my dad was in Europe, pretty sure that he was about to be shipped out to the Pacific for the invasion of the Japanese home islands. Which was guaranteed to be a meat grinder.
So dropping the bomb may have made my very existence possible. Hard for me to discount that.
I enjoyed the book, certainly a page-turner. It would make a good gift for a high school student interested in history. (Or for one you're trying to get interested in history.)
If I had but one quibble, I'd say the book misses a bet by not including Richard Feynman's Los Alamos stories, a combination of heartbreak (his wife Arline dying of TB in an Albuquerque sanitorium) and hilarity (circumventing security to the consternation of his colleagues, for his own amusement). That's told pretty well in Gliek's bio and Feynman's own memoirs compiled by Ralph Leighton,