The sacred capital of the Tang Dynasty, Chang'an City. Underneath the prosperity, there is an undercurrent. The bad guy Gu Shen, a petty official who just wanted to go around and collect his salary, was involved in a bizarre secret room murder case. The Minister of Rites suddenly died in a locked study room late at night. He died in a strange manner, with extreme fear on his face, but no scars on his body. As the investigation deepens, seemingly unrelated deceased persons appear one after another, and a palace secret that has been shrouded in dust for twenty years gradually emerges. Everyone may be the murderer, and everyone may be the next victim. In this huge maze, what Gu Shen has to do is not only to catch the invisible murderer, but also to save his own life from the entangled web of the powerful.
