Yi Sa doesn't want to teach anyone, but she has to, and the show knows the difference between those two things. The "Golden Soup" dives are genuinely tense, but the real pressure lives in watching her decide, moment by moment, whether this stranger is worth the cost of training him. Water Ghost lore builds slowly, each river clan rivalry revealing something about why Yi Sa carries so much weight alone, and the show doesn't rush you through it.

Where the Yellow, Yangtze and Lancang Rivers share a single source, three Water Ghost clans live along the banks: the Ding, the Jiang and the Yi. Water Ghosts can move through water at will and are skilled in geomancy and treasure hunting. Yi Sa, the last of the Yi line, operates an underwater bank on the Lancang. On a dangerous Golden Soup dive, she saves a man named Zong Hang. Searching for the truth and for a cure to her own fate, she trains him in the ways of a Water Ghost. Joined by Ding Yu Die of the Ding clan, the three head down into the primordial Ancestral Golden Soup.