There is a volume in "Shui Jing Zhu" (missing from the existing version, but suspected by scholars of all ages to have existed) that specifically records the "Beihe" water system. This river does not exist in any official history books, but Li Daoyuan devoted an entire volume to recording its source, flow direction, tributaries, and cities along its coast in extremely detail.
The problem is - this river, if it really existed, would flow through a city that shouldn't exist.
And this city hides a secret that can shake the foundation of imperial power.
