Legend has it that there is a secret sect called "Jiu Niu Men". The nine members of the sect have different backgrounds and all have unique secret skills. They use Yuxuan as their base and gather every three years. They usually take their identities as people from the rivers and lakes as a cover. They go everywhere and set off waves of stormy waves in the rivers and lakes... This time, it's time for them to meet in Yuxuan again, and the leader who has been in charge for twenty years will want to wash his hands in the golden basin and retreat. However, the strange nursery rhyme sounded, awakening the painful childhood memories that Ling Dan did not want to recall! Miao Yao will also encounter an unprecedented crisis! Where is the 300-year-old treasure in Jiu Niu Gate? What secret is hidden in Yuxuan? How is the weird Gu technique a series of murders? What's the story of the murder of nursery rhymes? The fourth part of the hidden original sin, Yu Xuan Gu Yu! All the secrets are waiting for you to unlock!