Shen Yan is a trainee delinquent in Wannian County, Jingzhao Prefecture (delinquent: a grassroots official responsible for arrests and public security in the Tang Dynasty, with a "low status" and low social status), 20 years old. In the early stage: He only believed in "evidence" and did not understand the world. He was ridiculed as a "nerd" by old delinquents, and he offended the powerful in the city due to his stubbornness during the investigation; in the middle stage: he learned to "supplement evidence with emotion", understood the people's suffering behind the case (such as poor households taking risks for survival), and began to protect his companions; in the later stage: when faced with the royal conspiracy, he adhered to his original intention of "the law is not noble", dared to confront the prince, and finally rehabilitated his father, and also protected the tranquility of Chang'an.
