Jiang Xun has a secret: he can taste the fear of the knife wielder three hours ago by licking the handle of the knife.
As an odor trace analyst at the Lancheng Public Security Bureau, his detection rate has always been 100%. Until he encountered a "smellless" study room - the rich man died on the chair, and there was no smell at all. Not cleansed, but like it never existed.
During the investigation, Jiang Xun discovered that the murderer was a man with no body odor. What's even more frightening is that he can make everything he touches lose its smell, including Jiang Xun's own sense of smell.
"It's not that I don't smell," the murderer said, "my smell is 'death' - you can't smell it because you're not dead yet."
Jiang Xun must find this "odorless man" before his sense of smell completely disappears. And the final truth lies in his mother who has been missing for twenty years...
