The Secret of Finding the Murderer

Because Li Zheng often had the same nightmare, he saw a village similar to his dream when he looked at the night scene. During this period, a folk song has been bothering him: "The big duck is sick, the second duck looks at it, the third duck buys medicine, the fourth duck boils it, the fifth duck dies, the sixth duck carries it, the seventh duck digs a hole, the eighth duck buries it, the ninth duck sits on the ground and cries, the tenth duck asks it why it is crying? The ninth duck says: The fifth duck will never come back once it is gone." Curiosity led them to the village to investigate the matter.