Three days before his death, detective Lu Xiao put secret files on seven unsolved serial murder cases into the hands of intern Chen Jin, and he was silenced in the interrogation room. Chen Jin discovered that each corpse had the same faded pocket watch, and the report of forensic doctor Shen Zhao, the keepsake of corpse collector Huo Ye, and the medical records of psychiatrist Lin Tang all pointed to an old case that had been sealed. When everyone thought the murderer was an insider of the police, Chen Jin found a note among Lu Xiao's belongings: 'What you see is not a dead person, but the truth they want you to see. '
