Ten years ago, he was the murderer, and she was the eyewitness.
Ten years later, he is a respectable university professor, while she is a first-year graduate student trying to set things right.
Why should a murderer get to live respectably behind a spotless mask? The eyewitness has endured ten years of torment. The moment she sees Qu Duanyang, Zhaoran decides to tear away the mask and expose the crimes beneath it. A new victim appears, bringing to light the corpse-concealment case at Zhiyuan No. 1 High School from ten years ago. The method is exactly the same, but the investigation turns up new clues. Who is imitating the case from a decade ago? The killer has already been caught. Is this just a clumsy copycat, or is it a warning from the eyewitness? Follow the clues and see if the real killer can be found! The truth is already plain to see.