It all started with Grandma Rong. The elderly matriarch had sent her grandson abroad to learn how to interpret dreams, never guessing that once far from home, young Zilai would ditch such an esoteric subject for courses in arithmetics and geometry. This is how the Rongs, a dynasty of salt merchants, turned into a modern family of mathematicians. After a few generations, Rong Jinzhen - the boy with the enormous head - demonstrated an astonishing ability to understand all the secrets of numbers. Too brilliant to go unnoticed, Jinzhen had to give up his academic career when, one rainy day, a cripple carried him off, with the aim of recruiting him for the cryptography division of the mysterious Unit 701. Jinzhen would go on to become the best cryptanalyst the Chinese secret services had ever known, but success came with a series of painful betrayals, as he found himself trapped in a system that subjected him to trials that were more and more inhuman, in a prison of secrecy and solitude.
