It tells the story that prosecutors in South Korea refer to evidence videos related to murder cases that are violent and cruel and are forbidden to be disclosed as "top secret files". After producer Kim Soo-chan learned that the videotapes were sealed in the underground storage room of the prosecutor's office, he accidentally obtained the relevant videotapes and decided to make a documentary based on them. Among them, he found that the Dongchengzhuang Hotel murder case recorded in the videotape in 1992 was surprisingly consistent with the Emeidong family murder case in 1987. What is the truth?