The story takes place in 1948. Yu Beiping (played by Chen Jianbin), an important member of the Special Investigation Bureau, was transferred to Qingcheng by his superiors and was ordered to investigate the murder that occurred there. In fact, Yu Beiping's true identity was being investigated and suspected by his superiors, and he was in danger all the time. In Qingcheng, Yu Beiping met a woman named Lin Sha (played by Qi Xi). As a lieutenant in the US Army, her true identity was actually Yu Beiping's long-lost daughter. Yu Beiping also has a little daughter named Xu Danni (played by Zhu Yanmanzi). At this time, she was attending university in Qingcheng and was involved in an unethical relationship with a married university professor. At the same time, the relationship between her and her father was also deadlocked because of Yu Beiping's special identity. Yu Beiping had to successfully complete the tasks assigned by his superiors, deal with cunning and insidious enemies, and endure the confusion and misunderstanding from his loved ones. He fell into a bitter battle.