The WWII topic inspires me to recommend Leo Marks' account of his war as the code master for the SOE; "Between silk and cyanide". Truly one of the best books I have ever read.

https://www.amazon.com/Between-Silk-Cyanide-Codemakers-1941-1945/dp/068486780X

When I was given it by my Mum for Xmas one year, I thought "Mmm. That looks quite big, and maybe a bit heavy going as it'll all be about codes; I'll leave it for the holidays".

I took it on holiday with me and could not put it down.

Giles. Mogless in Paris.