In the twenty-sixth year of the Republic of China, the ancient water town "Wuhe" in the middle and lower reaches of the Yangtze River was shrouded in a thick fog that persisted for days. Bizarre murders occurred one after another in the town: the deceased were found on their beds at midnight, their faces distorted as if they had seen ghosts, and a dried reed stuck in their throats. Their doors and windows were locked from the inside, and there was no trace of intrusion by outsiders. What's even more bizarre is that each of the deceased had seen a white-haired old woman holding a awning boat in the fog and heard her humming ancient nursery rhymes.
Foreign folklorist Shen Yanqiu came to Wuhe to investigate the lost local legend of "Water God Sacrifice", but was accidentally involved in a murder case. As the investigation deepened, he discovered that the deceased were all related to a "river sacrifice" tragedy that was deliberately covered up twenty years ago. In order to quell the "flood", the Lu family, a prominent family in the town, pushed a young girl into the river to sacrifice. The deceased today was the key figure involved in the incident.
In the thick fog, there are not only revengeful souls, but also living people using legends to cover up deeper conspiracies. As Shen Yanqiu traces the truth, people around him are in danger one after another: the sometimes crazy innkeeper's wife, the young master of the Lu family who behaves strangely, the boatman who helps secretly but whose identity is a mystery... Everyone seems to be hiding something, and what is hidden in that nursery rhyme may be the key to unlocking all the mysteries, and it is also a life-threatening charm.
