In January 1933, the Japanese army captured Shanhaiguan and occupied Chengde in March. The anti-Japanese situation in North China was in jeopardy. Shanghai's multinational forces are glued and undercurrent. Gu Pan, Tian Qiao Jie and Tan Zhong Wen are agents of Qingshan Military Academy. Gu Pan was alone in completing the assassination of the Japanese Economic Secretary, Koji Koji. Gu Pan was wounded to complete the mission, but was rescued by Wei Dong, an outstanding soldier. Under the guidance of Wei Dong, Gu Pan has been tested and entered the secret organization "Nest" to try to find out why he was framed. In the process of pursuing justice, Gu Pan gradually moved closer to the Red Revolution and used the "Hippo" as the codename to become a communist fighter.