The Quest for Kim documents the attempts, some successful, and some not, by author Peter Hopkirk, who has written a lot about India/central Asia and the Great Game period, to trace actual places and people in Kipling's
Kim. I've read several books by Hopkirk and enjoyed them all, including this one, which has dropped to $1.99 at Kindle and Kobo US.
However, with the novel as its focus,
Quest is a little different than Hopkirk's more traditional books, which are histories. I myself had read
Kim a long time ago, then read
Quest, and then got inspired to re-read
Kim, and enjoyed it in a different way with some of the background I now had.
Kindle US:
https://www.amazon.com/Quest-Kim-Pet...dp/B00GW4L0HK/
Kobo US:
https://www.kobo.com/us/en/ebook/quest-for-kim-1