In 1941, the Shanghai Concession became an isolated island. The Japanese army strengthened its intelligence blockade in an attempt to completely destroy the underground anti-Japanese organizations. Chen Mo, an undercover agent of the military command, relied on the golden finger ability of "Morse Code Shorthand" to lurk in the Translation and Telecommunications Section of the Japanese Military Intelligence Office, monitoring and intercepting Japanese military telegrams day and night. Lin Wan, the liaison officer of the underground party of the Communist Party of China, used his identity as a typist as a cover and became the only bridge between Chen Mo and the organization. When Chen Mo takes the lead in deciphering the top-secret telegram that the Japanese army is about to launch a large-scale "mopping up" of the New Fourth Army base areas, the two must, under the close supervision of Sato Ichiro, pass through numerous blockades and send the intelligence out safely. They fought against each other on the radio waves, walked on the tip of the knife, and composed a anti-war tragedy on the hidden front with their loyalty and wisdom.
