One night in Luocheng, the criminal police brigade suddenly received a call for help, and a shooting occurred in a community. On-duty detective Da Liu and police officer Meng Jin went to the scene and found that it was a dog killing case. Seeing that others were busy with major cases, the young police officer Meng Jin, who was eager to make meritorious deeds, felt very aggrieved, but Da Liu persuaded Meng Jin to conduct a detailed investigation of the case. Before leaving, Da Liu's son was beaten outside the school and hospitalized, but Da Liu had no time to see the child. To make matters worse, Meng Jin's girlfriend asked Meng Jin to transfer from the criminal police position, otherwise they would break up. Meng Jin apologized to his girlfriend, and his girlfriend left in tears. At this time, another armed robbery occurred in the City Center Hospital. The task force analyzed the trajectory, and Da Liu and others once again found traces of the "dog killing gun". The clues of the hospital robbery gradually focused on Li Chenghe. The task force made new progress in solving the case through the support of superiors in material and financial resources, using scientific and technological means, and a large number of clues. Through hard work, the task force further grasped the criminals, began to strengthen the security forces in key areas, and finally arrested the criminals Ding San and others. Luocheng returned to its former peace.