Xu Zhaoye, a modern counter-espionage officer, woke up one night and became a minor official in Lin'an Mansion of the Southern Song Dynasty who was about to be executed.
A secret letter theft involved him in the salt tea black account, the hidden secrets of the imperial city, old clan posts and border leaks.
He used account books to check people's hearts, used corpse marks to break the deadlock, and stood up from the dead. He organized night camps, inspected maritime trade, and organized border troops. Behind the lights of prosperous Lin'an, he guarded the first night gate for the impending Song Dynasty.
He left behind a volume of night travel records. Later generations only know that there was a group of nameless night watchmen in the Southern Song Dynasty.
