A series of murders modeled after famous mysteries from history, with a "shadow" symbol left at the scene each time. As the investigation deepens, it is discovered that these cases are related to an unsolved "Double Shadow Case" 20 years ago - after a pair of serial killers known as "Light and Shadow" committed many crimes, the "Light" was arrested, but the "Shadow" disappeared without a trace. The protagonist Sun Ying has multiple personalities. Let's see how he opens the door to the truth step by step~
