A fascinating novel - surprising and unfamiliar in its style and subject matter. Mai Jia is known as the father of Chinese espionage fiction, and he has evidently forged a completely new approach that to the genre, free of classic western (ie usually British) tropes and clichés. This probably explains why some were disappointed. It simply doesn't conform.

The central character, Rong Jinzhen, is elusive, an idiot-savant whom we never really understand; yet he is always compelling and poignant. We learn of his mathematical and cryptological genius but the book never gets bogged down in the science (as could so easily have happened). The Chinese state looms large over everything, and in some ways, this is a book about individuals having their lives and even identities subsumed into the state's greater good. Autonomy is never really an option. Yet in the midst of this overpowering atmosphere, there are moments of humanity and self-sacrifice. This is a world of total secrecy and incorrect surmises and guesswork.

But the key relationship is between Jinzhen and Prof Liseiwicz - the two great minds involved in the coding and decoding business of the book. The quest is the breaking of PURPLE and BLACK codes - and the professor initially tries to warn his protegé off cryptography because of its threat to mental stability. But as the layers are gradually peeled back in the course of the book (written in the style of a journalist writing an official history, and so interspersed with transcripts of interviews with the key individuals), the picture gradually sharpens into a melancholy and poignant whole.

Brilliantly written in sparse, and deceptively simple, style, this opens up fleeting glimpses into a world that is alien to most.