This tells the story of the different stories of several grassroots police officers in the Waitan Police Bureau in Shanghai. The police chief Ma Xingguo, nicknamed the "old mage," with his rich life experience and experience in handling cases, can mediate disputes and solve them, but he is not computer literate, does not know foreign languages, and often encounters new problems in his work; The deputy police chief Lu Yi, with a tough and cold appearance and a modest and introverted personality, has many banners of recognition, but also a lot of small isusues, which require the old mage and even new police officers to "solve" the cases; The beautiful police girl Yuan Yuan comes from a privileged family, but she is enthusiastic and chivalrous and tender-hearted; Nicknamed "Master Yang," Yang Junyi is fluent in foreign languages, he pursues logic in everything and advocates for a western-way of doing things; "Rookie" Jiang Nan is a trainee police officer, yet the trival and tedious community policing work has subverted his dream of being a criminal police officer, but the seemingly simple police work has been a lot of turns, but also let him continue to learn new things everyday......