The play tells the story of Lu Dongzhi, a kind-hearted but always bullied and ignored good guy. He couldn't speak out his grievances, so he chose to commit suicide, but the place where he committed suicide happened to be the murder scene of a serial killer. He was scared away, but was hit by a car on the road. After waking up, he lost his memory. Instead of his lost memory, a diary suddenly appeared in his hand. The diary recorded all the criminal evidence of the perverted killer. Because of various coincidences, Lu Dongzhi mistakenly thought that the owner of the diary was himself and thought that he was a perverted killer. Yoon Shi-yoon plays Lu Dongzhi, who is a low-level fund manager. He works as a small clerk in a securities company and has been responsible for various chores for several years. He is very timid and soft-hearted, so he is always used by others. He can't refuse all kinds of unreasonable requests. The team leader only thinks of him when he has no place to vent his anger. His colleagues of the same period have been promoted, and even the rookies who have just joined the company look down on him. But he has never been angry, and he is a veritable bad good among bad good people. Zheng Renxian plays the policewoman Shen Baojing, who has innate talents but is always ignored. She dreams of becoming a profiler, but in real life she is patrolling and has never been in charge of a case that can be considered a case.