It tells the thrilling journey of Chen Lin (codenamed "Qingsong"), an underground member of the Communist Party of China, who impersonated his identity as a special commissioner for military reunification and sneaked into the core of the Kuomintang's secret service on the eve of the fall of Wuhan in 1938. Responsible for obtaining the Kuomintang's anti-communist plans and Japanese military intelligence, he relied on his cryptography expertise and special agent training to calmly handle identity verification and code-breaking tests, and initially won the recognition of Division Chief Xu Enzeng. The story highlights the protagonist's sense of crisis as he walks on the edge of a knife through the chaos of the pier and the gloomy environment of the secret service. It also lays the groundwork for the subsequent dealings with the secret service leader Dai Li, and demonstrates the cruelty of the hidden front struggle and the firm belief of underground party members.
