On the eve of the Songhu Battle in 1937, Shanghai had become the "Far East Spy Capital" where various forces competed.
Chen Mo, the military's ace agent "Deep Sea", was ordered to lurk in the "No. 76" Core of Wang's puppet agent headquarters, dealing with the Japanese chieftain Doihara and the spy leader Ding Mocun. After a secret contact fails, he encounters a mysterious and elegant "Mrs. Cheng" - who is actually Lin Yanqiu, an underground member of the Communist Party of China.
From mutual testing and suspicion to being forced to cooperate, the two jointly performed a series of near-death missions: stealing the Japanese Yangtze River defense map, rescuing Jewish scientists, and smashing the Japanese "Sakura" chemical weapons plan...
Every mission is an ultimate game of intelligence and courage. When the "Huang Daofu Plan" surfaced, a conspiracy that could destroy the entire wartime economy enveloped Chongqing and Yan'an, this pair of "fake couple" agents who walked on the edge of the knife had to make the ultimate choice: to be loyal to their respective camps, or to their inner conscience and beliefs?
In the long night, they used their faith as a blade and vowed to cut through the last darkness before dawn.
