The story takes place in Lujiang City. Ding Chao was instructed to kidnap Zhang Dayang, the president of Lidu Group, a construction giant in Lujiang City. Ma Yunshan, deputy director of the Municipal Public Security Bureau, commanded the criminal police team and successfully rescued the hostages, which was highly praised by Chen, deputy secretary of the Political and Legal Committee. Ding Chao died inexplicably in the hospital, which made Chang Jian, deputy captain of the criminal police detachment, very annoyed. He believed that Ding Chao's case was related to the "Lan Ping Da Xia Case" that killed three policemen three years ago. In order to strengthen the team building, the Municipal Public Security Bureau adjusted the Municipal Bureau Inspection Brigade. Chang Jian was transferred to the Inspection Brigade as the captain, and he couldn't figure it out. He once vowed that he would not wear a police uniform in vain if he did not solve the "Lan Ping Da Xia Case". Liang Yunpeng, director of the Public Security Bureau, ordered Chang Jian to take office, saying that Chang Jian was a soldier and should understand that military orders are like mountains! Chang Jian took office. The first mass complaint case he handled after arriving at the inspection brigade was that Xiang Dongping, the chief of the police investigation section of Jiangping Branch, intervened in the family dispute between Huang Jinding and his wife Shan Kehong. Xiang Dongping's father-in-law was Chen, the deputy secretary of the Political and Legal Committee, Chang Jian's old superior. When handling this case, Chang Jian had a fierce conflict with his old comrade-in-arms, Ma Yunshan, the deputy director of the Municipal Bureau. He believed that Chang Jian had a prejudice against Jiangping Branch. But to his relief, the Party Committee of the Bureau supported him from beginning to end, the inspection team members supported him sincerely, and many ordinary police officers consciously accepted their inspections, and the people praised them from the bottom of their hearts. Jinding Group and Zhang Dayang's Lido Group competed with each other for the "Golden Eagle Building" project. When the investigation of Ding Chao's case was making progress, Chang Jian's sister Qingqing was mysteriously recruited to Jinding Group as a manager of a department. Chang Jian wanted Qingqing to withdraw from Jinding Group, but Qingqing refused to listen and had a grudge against Chang Jian. Xiao Xiaona, a TV reporter, hosted the "Police Focus" column and often went to the inspection team for interviews, which caused Qingqing to misunderstand her brother. Chang Jian was framed and had no way to defend himself, so he was forced to stop working. Xiong Weigang didn't believe that his master would accept bribes. Chang Jian was a strong man and became ill when he was angry. His wife Chunxue was already ill, and her old illness relapsed because she was taking care of Chang Jian. His sister ran away from home because she couldn't get into the TV station. Chang Jian's family was in crisis. In the crisis, two beautiful women came to help, one was Ge Mei, a female police officer of the inspection team, and the other was Xiao Xiaona, a female host of the TV station. Ge Mei's support for Chang Jian caused a lot of discussion among colleagues. Xiao Xiaona admired Chang Jian's uprightness and frankly took care of Chang Jian's wife who was critically ill. Xiang Dongping relied on his father-in-law, repeatedly violated discipline, and eventually went to death. Jiang Chong, who was "undercover" inside Huangjinding, provided evidence that Huangjinding framed Chang Jian, and Chang Jian returned to his post. Huang Jinding, who was hiding behind the scenes, was desperate and hired someone to assassinate Chang Jian. However, his cleverness backfired and he dug his own grave step by step. Qingqing was kidnapped by Huang Jinding's accomplices, and Xiong Weigang died heroically in the fight with the criminals. At the last critical moment, Ma Yunshan chose to repent and reflect, and uncovered the mystery of "Lan Ping Xia". "Police in Police" is not only about inspectors, but also praises the outstanding members of the people's police, including Liang Yunpeng, the director of the Municipal Public Security Bureau, Xiong Weigang, the captain of the criminal police brigade of Jiangping Branch, and Shang Bing, the former director of Jiangping Branch, who made mistakes but finally defended the honor of the people's police with his life... They defended the building of the Republic with their blood and lives, eliminated those corrupt and black forces with justice and law, and protected the lives and happy lives of hundreds of millions of people with their loyalty.