In 1946, the domestic situation was turbulent and civil war was imminent. A group of 38 top military elites were setting sail for the United States, but an accidentally lost notebook revealed the existence of an undercover on the list. In Nanjing, where agents were everywhere, the US and Chiang Kai-shek spies secretly colluded and planned to eliminate the undercover "target number one" on the list. The two armies were engaged in a thrilling game over "who is the undercover". When will the "target number one" lurking in the dark show up? Can it turn the tide of the civil war? The life-and-death secret battle is suffocating...