Liu Dan, a top student at the police academy, accidentally died in a security mission. He traveled back in time to the period of the Wang Puppet National Government and possessed a police student from the police academy of the Ministry of Police. Liu Dan knows that this era is in turmoil, and he needs to stand firm in these troubled times and use what he has learned to contribute to the country. Relying on the professional knowledge and keen insight learned in the police school in his previous life, Liu Dan quickly stood out in the school. Whether it was the elaboration of criminal investigation theory or the demonstration of practical skills, he far surpassed other students. He also became famous when he helped the school solve a school theft case with his precise analysis. After graduation, Liu Dan was assigned to work in the Capital Police Department of the new government. At that time, there were many factions in the police department, and undercurrents from all sides were surging. Liu Dan faced many complex cases as soon as he joined the company. Once, a mysterious jewelry robbery occurred. There were very few clues at the scene, and the police had no clue for a while. Liu Dan deduced the robbers' modus operandi and escape route through careful investigation of the scene traces and interviews with surrounding residents. He followed all the way and finally wiped out the gang of robbers and recovered the stolen jewelry. The cracking of this case spread Liu Dan's reputation in the police community, and various forces began to pay attention to him. The Japanese secret service took a fancy to Liu Dan's ability and wanted to win him over for their own use, promising to give high-ranking officials generous salaries. At the same time, the underground party organization also contacted Liu Dan through secret channels, hoping that he could pass on information for the anti-Japanese cause and save the people who were in dire straits. Liu Dan struggled in his heart, but strengthened his belief in fighting for the country and nation. On the surface, he promised to serve the Japanese secret service, but in fact, he secretly cooperated with underground party organizations.
