多年来，一个令尤小（Zeng Yi 饰）难以放下的事情一直遥遥 lurking in his heart – a heinous serial murder of women that occurred 17 years ago, a case he was responsible for investigating as a detective. The cunning killer skillfully eluded the grasp of justice, until the day the statute of limitations expired and the murderer escaped the wrath of the law completely. The families of the victims, in despair, expressed their indignation towards the powerless police force and the brutal criminal.
Just when everyone thought the darkness cast by this tragedy would soon dissipate, the publication of a book titled "I Am a Murderer" left everyone in shock, with an unexpected author – none other than the mastermind behind the 17-year-old murder case, Li Douji (Pidi Shihuo 饰). However, as a detective who had pursued the killer, Yue Xiao did not believe that Li Douji was indeed the perpetrator. A fierce game of cat and mouse unfolds between the two, as Yue Xiao seeks to expose the truth behind the mask of deceit.
