This film is adapted from the real deeds of public security hero Li Bei. It tells the story of Li Lu, a female police officer who yearns for the front line of criminal investigation, who is assigned to the patrol police brigade as acting captain. Li Lu, who devotes herself to the grassroots, is not afraid of rumors and misunderstandings. She insists on setting an example to solve problems for the people. She leads the police team to assist in criminal investigation and solve the case of family annihilation in the community, fights bloody battles with human traffickers regardless of life and death, and subdues the illegal speeding gangs who attack the police. In the day-to-day grassroots work, Li Lu builds trust and friendship with the police officers, and leads the team to quickly grow into an excellent patrol brigade that is well-trained and united, protecting the lives and property of the people and maintaining social tranquility.