In 1939, after the fall of Shanghai, the concessions, special higher education courses, remaining military lines, and underground transportation stations were intertwined with each other, and the city was cut into disconnected intelligence faults. The male protagonist was originally a military secret agent. Due to a top-secret radio exposure case, his superiors suspected that he had "lost the line" and was forced to prove his innocence between the enemy and ourselves. The heroine is a traffic officer lurking in the Japanese and puppet economic agencies. She holds the end of an intelligence chain that has been artificially cut off. She is also the only person who knows the truth about the "fault". The two went from being wary of each other to being bound to life and death. In the fight for a lost code book that affected the deployment of frontline battles, they gradually uncovered the inner ghost hidden in their own high-level officials.
