Thoroughly enjoyed this (audible listen). It tells the tale of the rockets launched by Nazi Germany at Britain during WWII, specifically London. The story has numerous threads and POV characters, told from both sides of the war.
The underlying message I took from the book is delivered in the last chapter, where our protagonists from England and Germany meet, and come to realise they had both been lied to, and that what each had heard about the other was not true at all.
War is always avoidable, it is not countries that go to war, but contrasting ideas, beliefs, and the lengths certain people are willing to go to enforce them.