Captain Sam Wyndham, former Scotland Yard detective, is a new arrival to Calcutta. Desperately seeking a fresh start after his experiences during the Great War, Wyndham has been recruited to head up a new post in the police force. But with barely a moment to acclimatise to his new life or to deal with the ghosts which still haunt him, Wyndham is caught up in a murder investigation that will take him into the dark underbelly of the British Raj. A senior British official has been murdered, and a note left in his mouth warns the British to quit India: or else. With rising political dissent and the stability of the Raj under threat, Wyndham and his two new colleagues - arrogant Inspector Digby, who can barely conceal his contempt for the natives and British-educated, but Indian-born Sargeant Banerjee, one of the few Indians to be recruited into the new CID - embark on an investigation that will take them from the luxurious parlours of wealthy British traders to the seedy opium dens of the city.