Cheng Zhou, the deputy leader of the serious crime team, was at a key point in tracking down the serial murder case "Rainy Night Butcher" when he was attacked and fell from a building in an abandoned factory. After waking up, he lost his memory for nearly ten years. The former criminal detective has become an "outsider" that even his colleagues cannot recognize. Only a black notebook filled with case details and private thoughts is his only link to the past. After losing his memory, Cheng Zhou's brain seemed to be restarted. His sensitivity to logic, numbers and micro-evidence increased exponentially, turning him into a high-IQ crime-solving machine. Relying on the "old clues" in his notebook and combining it with "new logic", he successively solved unsolved cases such as old corpse cases and safe theft cases. As the investigation deepens, the torn pages in the notes, the cross symbol that highly overlaps with the "Rainy Night Butcher" mark, and the secret records of Jiang Yishan, his best friend who disappeared mysteriously three years ago, all lead him to an even more shocking truth.
