For centuries, Alexander the Great's city of Alexandria Beneath the Mountains was a meeting point of East and West, but then it vanished. In 1833 it was discovered in Afghanistan by Charles Masson, a deserter, pilgrim, doctor, and archaeologist. While tracing the history of this remarkable kingdom, Edmund Richardson profiles Masson, a master of disguise who drank tea with kings, traveled with holy men, and uncovered incredible treasures, even as he spied for the East India Company and possibly even Russia.