Death in the East / Abir Mukherjee.

Calcutta police detective Captain Sam Wyndham and his quick-witted Indian Sergeant, Surrender-not Banerjee, are back for another rip-roaring adventure set in 1920s India. 1922, India. Leaving Calcutta, Captain Sam Wyndham heads for the hills of Assam, to the ashram of a sainted monk where he hopes to conquer his opium addiction. But when he arrives, he sees a ghost from his past a man thought to be long dead, a man Wyndham hoped he would never see again. 1905, London. As a young constable, Sam Wyndham is on his usual East London beat when he comes across an old flame, Bessie Drummond, attacked in the streets. The next day, when Bessie is found brutally beaten in her own room, locked from the inside, Wyndham promises to get to the bottom of this. But the case will cost the young constable more than he ever imagined. In Assam, Wyndham knows he must call his friend and colleague Sergeant Banerjee for help. He is certain this figure from his past isn't here by coincidence, but for revenge.