In the ninth year of the Republic of China, the "Yanliu Crossing" in the Jiangnan water town was shrouded in white fog all year round for three months. The "Shenyuan Pavilion" near the river in the west of the town was originally a library built by wealthy merchants a hundred years ago, but now it has become a dangerous place that no one should approach - three young men who ventured into the pavilion disappeared one after another, and their bodies floated on the river a few days later. Their necks were covered with smelly water plants, and a blackened iron needle was embedded between their eyebrows. The death state was exactly the same as the "water ghost seeking life" recorded in "Old News of Yanliu Crossing".
Xie Yanci, a former criminal police officer in the French Concession in Shanghai, was framed and dismissed by the police station. He returned home with the disappearance of his old friend that had not been solved for three years. He was involved in the whirlpool as soon as he stepped into Yanliu Ferry. At the same time, Liu Tinglan, a folklorist who graduated from Peking Women's Normal University, is investigating the mystery of her father's disappearance. The last note left by her father only read the words "Shenyuan Pavilion, Nine-section Calamus, and Hebo Festival".
The two went to the attic together to find out the truth, but found that the bottom floor of the attic concealed a secret passage leading to an underground river. The walls were covered with strange sacrificial totems, and there were countless puppets with black eyes floating in the underground river. As the investigation deepens, strange things happen one after another: nursery rhymes echoing late at night, paper lanterns suddenly appearing in front of every house, doors and windows entangled in water plants, and dark shadows flashing in the mirror...
The thick fog at Yanliudu is by no means a natural phenomenon, but the result of a sacrifice that died a hundred years ago; Shen Yuan Pavilion is not a library, but a cage to suppress "He Bo". When the ninth paper lantern lights up, the missing father suddenly appears, bringing with him grievances and conspiracies spanning a century, pushing Xie Yanci and Liu Tinglan to the edge of life and death. They must decipher the secret language of the iron needle and find the nine-section calamus before the fog clears. . .
