Student Policemen Investigated Crimes and Tracked Down Japanese Spies in the Republic of China

Zhang Yuchen, a student at the Public Security University, found an old writing brush in Panjiayuan. This pen could actually draw a door to the Republic of China on the wall. From the beginning of the investigation to the final tracking of the spy, as the incident continued to escalate, a series of incidents occurred. Zhang Yuchen felt that he had to seek help. Was he seeking help to organize a confession and seek national cooperation? Or recruit your own troops...?