The story is set in 1941 when Shanghai falls into the hands of the enemy.
Street hoodlum Chen Shan, who looks confusingly similar to military special agent Xiao Zheng Guo, catches the eye of Japanese special agent Huang Mu Wei. Mu Wei abducts Chen Shan’s sister Chen Xia and forces Chen Shan to work as a spy for the Japanese. In order to save his sister, Chen Shan agrees to go through a special training and subsequently pretends to be Zheng Guo.
He goes to Chongqing and lives together with Zheng Guo’s wife, Yu Xiao Wan. In Chongqing, he meets Zhang Li, who is an underground member of the Communist Party hiding in the army, and falls in love at first sight. Thanks to Zhang Li, Chen Shan comes to understand about his responsibility as a Chinese citizen and eventually joins the Communist Party.
While working hard to break free from the control of the Japanese as well as the military and save his sister, Chen Shan also fights alongside Zhang Li and other members to lead the Party to victory.