The film "Yinmu Detective Letter", adapted from the popular horror novel of the same name, has released a pilot notice. Has Yinmu Credit Bureau received a new Case? The original book tells the story of the growth of a stone with Yin and Yang eyes since childhood. It has been living next to ghosts for more than ten years, seeing the separation of life and death, and the different paths of people and ghosts. As the son of Hong Kong's richest man, Wu Pol-leung has a shocking secret passed down from generation to generation. When the time comes in the university ghost dormitory, can Shi Tou and his new acquaintance Wu Bolang and the eccentric PATRICK work together to prevent the ghost door from opening?