I read his book when I was still doung my physics studies. It starts with a description of the first experiments with radioactvity (Hahn, Rutherford, Fermi, ...), to the first theretical models (Bohr ...). Then they describe very detailed the researche done for the Alamo project, the difficulties there and why they started it so on. Very clear, without emotions. Then the bomb trops on Japan. How thes chose the target, the conditions, describtions of the people that survived. I have to admit that I did not sleep very well that week.
After that I started my conscientious objection.