One of the authors was there, on one of the ships that wasn't sunk. There is a great amount of detail about the build-up, the ships, the convoy up to and after the fatal order to "scatter", and a good chunk of the book is about the survivors in Russia; which ironically is different to what I've read in other books about cold and heartless Soviets completely ignoring them - there is some of that in this book, but also a fair amount on the ordinary people, especially the women, whom the writers clearly regard as a breed apart! The "scatter" order itself is dealt with at the end - there's actually nothing in the book until then about what was going on away from the ships in the convoy eg the Admiralty, the Allied Governments or the British Home Fleet.
The conclusions are interesting, although not really going into any depth. The writers are more critical of the 15-year secrecy from the Admiralty than the order itself. They are also, interestingly, critical of the Germans - they argue that with what they had, the Germans should have wiped the convoy out with ease (four Uboats were involved in attacking one of the merchantman).
I'd recommend this. I'd probably also recommend that it not be the only book you read about PQ-17.