A Necessary Evil by Abir Mukherjee

Set in 1920s colonial India, a British detective and his Indian sergeant witness the assassination of a progressive prince and follow the trail from Calcutta to the glittering yet treacherous princely state of Sambalpore. Amid palace intrigue, diamond wealth, religious tensions, and imperial politics, they navigate rival factions and hidden alliances to expose a conspiracy tied to the victim’s reformist ambitions. Their pursuit of the truth forces them to confront the moral ambiguities of justice in a world built on power and compromise.