Ten years ago, a case in the name of "euthanasia" made the protagonist Kevin the target of public criticism, and several families were torn apart because of him. Ten years later, in order to uncover the truth of the year, neuroscientist Jiang Chabai took the risk and entered a memory fragment of the murderer into the young police officer Shen Yi - deep in that memory, there was a treacherous puzzle about "mercy" and "sin", and Kevin's name was always a sharp knife hanging over everyone's head.
