Fang Yuan, a military agent who lurks in a second-hand bookstore in Liulichang, Peking, appears to be a taciturn and erudite "bookworm", but in fact, he transmits information through pinhole cipher text on the margins of ancient books. When a fragment of the "Yongle Dadian", which was about to travel east to Tokyo, actually contained all the lifeblood of the Pingjin underground radio stations, he was in a desperate situation: being ordered to escort was treason, and disobeying the order would lead to death. In this silent secret war unfolding among the piles of old papers, he must deal alone between the enemy and ourselves, guarding the top secrets amidst the ink and spy shadows, and uncovering the hidden shadows of the organization.
