In spring, Shen Yanzhi, the county magistrate of Xun'an, receives a complaint from an old woodcutter named Wang, who beats the grievance drum. Wang explains that while gathering firewood at the foot of Mount Wangyue, his strong, well-fed working donkey was secretly swapped for a skinny one. Through careful observation, Shen Yanzhi discovers clues in the mud on the donkey's hooves, traces of leftover fodder, and marks around its neck. Combining these findings with Wang's description of the suspect, he identifies Liu Chengyu, the young master of the Liu family. After a confrontation and interrogation, Liu Chengyu confesses that he swapped the donkey out of sheer mischief. Shen Yanzhi delivers a fair judgment, ordering him to return the original donkey, compensate Wang for his losses, and kneel publicly as punishment. The donkey is ultimately returned to its rightful owner, demonstrating Shen Yanzhi's commitment to serving the people with integrity and impartiality and preserving peace in Xun'an County.