The Purple Sapphire' revolves around two Americans, John Ford and his niece, Rosita Rowe, both gem traders and explorers working mainly in central Asia. When they were temporarily staying in Darjeeling, in North India, the British general Wedderburn asked them to engage in an unusual quest. They were assigned to search for the general's 8-year-old daughter, Evelyn, who had been kidnapped 12 years ago. Filled with mysteries and plot twists, this work keeps the readers curious till the end.