The hero of Dark Diamond is Lord Shayista Khan, the Mughal Viceroy of Bengal, who in 1685, during Aurangzeb's rule, was the most powerful man on Earth. Under Lord Khan's governance, Bengal became the epicenter of commerce and culture - a veritable treasure chest with greedy enemies: Maratha warriors, Arakan rajas, Hindu zamindars, fanatic Mullahs, a diabolical Pir with occult powers and the East India Company. Not only does Lord Khan have to keep them at bay but also he must neutralize the curse of the Kalinoor, the dark diamond sister of the famous Kohinoor that now adorns the British Crown.