Reading Rudyard Kipling's Kim has me looking for a nonfiction book about the Great Game, the 19th / 20th century proto-Cold War between Russia and the US over control of Central Asia. (At least, it was something like that. I haven't read the book yet.)
Internet research seems clear that this is THE book to go with. Fun and influential, if slightly pro-British (a problem no other book I found seemed able to solve).