A Necessary Evil by Aber Mukherjee is the second book featuring Surrender Not as the Sergeant to the opium-addicted British detective Captain Sam Wyndham. They are part of the police force in Calcutta in the post-WWI Raj, where the rumblings for independence are growing louder. The books are distinguished by a very strong sense of place and interesting historical background. The characters are well developed and the plot escalates the tension realistically. You will learn a lot about the politics and daily lives of all castes in this era in India while a tricky murder mystery is untangled.