This film tells the story of 27 corpses being hung in the street overnight, with their bones removed and their deaths strange. Song Ci, who has always been skeptical, investigates in depth with his female assistant Yu Mo in an attitude of pursuing the ultimate truth. Through the investigation of the deceased's network of relationships, Song Ci discovered that this was a random murder case. The valuable thing was the number "27", which was related to the Bo Xun case ten years ago. He asked his mentor Geng Zhinian for advice, but who knew that the 27 corpses spontaneously combusted in the government office that day. Although they were reduced to ashes, there were traces to be found. Song Ci had to suspect that all this was related to Geng Zhinian, who was in charge of the Bo Xun case that year. At the same time, Yu Mo, who has a secret life experience, has gradually approached the "truth", which is a truth that she cannot accept either...