The Strangler Vine

Others have described this as an historical detective novel, although it's not really a detective novel at all. It's more of political mystery set in India in the early 1800s, when the British were attempting to rule India–a unique setting, for sure. While it had its dry spots, there was a genuinely surprising (for me, at least) plot twist. I will read the second in the series, since I liked the main characters.