Episode 1: Morning Sir finds the mysterious phone
A crime of passion takes place at a supermarket and the wife is suspected of murdering the mistress. Morning Sir leads his team to the crime scene to conduct an investigation. His subordinate, Ruan Zhigao, believes the wife is the murderer, but Morning Sir feels otherwise and combs the crime scene thoroughly. At that moment, Gao Shan appears and claims she witnessed the murder but her account is incomplete due to her physical impairment so she instead makes inferences from what she has seen to deduce the sequence of events. However Morning Sir refuses to admit Gao Shan's deduction as a police statement because he places great emphasis on physical evidence.
Morning Sir's mother, Zhang Yue Ping, is a law enforcement officer. Her husband, Dahe, was also a police officer who earned notoriety for setting a murder suspect free 20 years ago. He was later found dead on a prostitute's bed. Yue Ping hardened her heart toward men after that incident. Since Dahe's death, mother and son have been dependent on each other, and are good buddies at work and at home. As a result of his father's death, Morning Sir now hates unfaithful men. He has also been working continuously on the "severed leg" homicide case. Dahe oversaw the case 20 years earlier but let He Zhengnan go, and the latter has been scott-free all this while. Morning Sir resolves to crack the case to atone for his father's shame.
Continued investigations into the crime of passion reveals that Gao Shan's deduction was correct but Morning Sir thinks it's a lucky guess on Gao Shan's part. Gao Shan is a handicapped novelist who uses materials on true crime cases in her stories. She is greatly interested in the "severed leg" homicide case and believes He Zhengnan isn't the murderer. Li Shijing, Gao Shan's cousin, is a junior female police officer who has just been transferred to Morning Sir's team. While trying to catch up with Shijing, who had gone after a pickpocket, Gao Shan discovers a doll box containing a severed leg in a rubbish heap in a back alley. Morning Sir thinks He Zhengnan was behind it.
Around the same time, Morning Sir also discovers a phone amongst his late father's possession, and that phone surprisingly works... ...