In a dilapidated corner of the city, an old policeman with a bald head in the serious crime squad has been on the job for 30 years. Although he has solved many major cases and is covered with scars and bullet holes, his family situation is a mess. His wife divorced him and his son thinks he stinks. In contrast to the old policeman, the young private detective Bobby (voiced by Huang Lei) is in his prime, rising rapidly. The FBI invites him to give lectures, and related cartoons are popular. Bobby has become a Sherlock Holmes-like existence. After a murder case in a closed room, the old policeman had to invite Bobby to investigate. Why is Bobby so powerful? It all seems to be related to his mother, Mrs. Mai (voiced by Sandra Ng). Under the questioning of the children who admire him, Bobby's thoughts return to his childhood, the happy and carefree childhood that McDull (voiced by Zhang Zhengzhong) and his mother shared. Everything good has long been destined...