Disappointing finish to what was an interesting character study at the beginning. Basically I enjoyed the book until Jinzhen was taken from the university and brought to the cryptography section. Here the book loses all momentum, there is no cool spy stuff, the author treats us like idiots incapable of grasping any technical aspect of the work and merely throws out some ridiculous analogies to explain the code breaking, propagandist phrases about sacrificing for the nation enter the work (can't tell if these were supposed to be ironic, but I assumed they were not), and all the characters introduced from here on are flat and uninteresting. Probably would have enjoyed the work quite a bit more if they would have left Jinzhen and his father working on the artificial intelligence question.