India, 1920. Captain Sam Wyndham is visiting the kingdom of Sambalpore, home to diamond mines and the beautiful Palace of the Sun. But when the Maharaja’s eldest son is assassinated, Wyndham realises that the realm is riven with conflict. Prince Adhir was unpopular with religious groups, while his brother – now in line to the throne – appears to be a feckless playboy. As Wyndham and Sergeant ‘Surrender-not’ Banerjee endeavour to unravel the mystery, they become entangled in a dangerous world. They must find the murderer, before the murderer finds them.