A Communist spy serving as an officer of the Japanese puppet regime joins hands with Russian and Korean spies to execute an assassination plot. In the year 1941, Nazi Germany declares war against the Soviet Union. Given that Manchukuo's loyalties lie with Cheng Tian, the Russians are caught in a situation where they face threats on all sides. Their intelligence agency devises a long-term plan in secret. Communist spy Tang Fei (Liu Yunlong) receives a mission to infiltrate the enemy by pretending to be one of their own. At the Security Bureau, he crosses paths with Cai Meng (Han Chae Young), a woman determined to fight against the Japanese regime. They gain each other's trust as they try to outsmart the enemy within their own territory.