At the turn of the spring and summer of 1945, Communist intelligence worker Song Zhuowen successfully sneaked into the Harbin Secret Service of the puppet Manchukuo. Song Zhuowen's extraordinary reasoning ability and thoughtful and meticulous style won the appreciation of his superiors. At the same time, he also attracted the jealousy and secret strife of his colleagues. In order to find out where the arrested Communist Party members were secretly detained, Song Zhuowen took advantage of his familiarity with the work process to follow the clues, find the secret detention point, and rescued the underground party members. Several operations of the Secret Service were frustrated one after another. Guan Xue, the chief of the Secret Service, believed that there was an insider and began to investigate. Song Zhuowen successfully got rid of suspicion by taking advantage of the complex interpersonal relationships within the secret service. He continued to fight in dangerous environments, resolved crises many times, and completed many difficult tasks such as obtaining the enemy's garrison patrol route map. However, he was exposed after obtaining intelligence on a secret weapon being developed by the Japanese army. He was shot and fell to the ground during the retreat. The organization successfully rescued him and covered him to leave Harbin.
