Sinopsis: The modern office worker Yang Ling unexpectedly enters the fantasy-filled Da Feng Dynasty and takes on a new identity as Xu Qi An, a night watchman known as a "copper gong," responsible for supervising officials and solving cases for the people of Da Feng. Using his modern knowledge, scientific understanding, and reasoning skills, he successfully cracks one bizarre case after another, earning the title of Da Feng’s top investigator. In this world filled with monsters, magic, complex human relationships, and hidden dangers, he and his like-minded companions bravely face challenges, willing to sacrifice themselves to fight against the dark forces within the court. Together, they speak up for justice and the people, united in protecting the peace and stability of Da Feng.