In August 1937, before the Battle of Songhu, Lan Yanzhi, the eldest daughter of the Lan family in Shanghai, was accidentally involved in the confrontation between the Kuomintang National Salvation Association and the Japanese Special High Section because of a box of rouge, and uncovered the lurking Japanese spy, Feng Zixiong, the director of the Shanghai Military Supply Department. However, he was the father of Yanzhi's best friend Feng Manna. Feng Zixiong resisted arrest and died tragically. Manna hated Yanzhi from then on. At the same time, Feng Zixiong's offline spy "Shadow" died in the Kuomintang's anti-traitor operation. Zhou Yuhao, a Communist intelligence officer who was lurking in the same department as him, boldly pretended to be "Shadow" and reversely infiltrated into the Japanese Special High Section. During this period, he also became acquainted with Yanzhi and Manna. With the fall of Shanghai, Yanzhi officially became an agent of the National Salvation Association. And Manna betrayed her country because of hatred, and also became an agent in the Special Warfare Headquarters of the Japanese spy organization. Zhou Yuhao has always wanted to win Manna back, but Manna's hatred for Yanzhi is too deep to extricate herself. In the spy war in Shanghai, Yanzhi and Manna, two former sisters, launched a brutal showdown...