In early 1931, the business prodigy Guan Yuda (later alias Han Shan) accidentally became a spy. After being hunted down and divorced with his new wife (Zuo Xiaoqing), his pen name entered the Japanese Secret Service. Seeing his wife again, unable to recognize him because of his mission. Juntong agent Fang Kun (Wu Gang) falls in love with his wife and is deeply saddened. In the choice between big love and little love, the CCP agents launched a desperate struggle with the enemy with amazing perseverance and extraordinary wisdom. On the eve of victory, the tacit understanding between relatives was exchanged for blood.