In the 1930s, Peiping was in turmoil, plagued by external and internal troubles. Former police detective Zhou Xiuyuan was dismissed for his integrity and truth-seeking, but he returned to the front line of investigation when his friend was murdered mysteriously. Joining hands with newspaper reporter Song Jinyao, military agent Qin Mobai, and revolutionary party doctor Su Nichang, they are involved in various unsolved cases involving military politics, famous families, rivers and lakes, and the underground world. Under the surface of each case, there are hidden power games, interest disputes and tests of human nature. In the process of pursuing the truth, the protagonists not only increase their trust in each other, but also constantly explore their own weaknesses and growth. Multiple story lines go hand in hand, and the hidden mastermind and past secrets are revealed layer by layer. It is not until the end of the troubled times that all the mysteries and fateful entanglements finally come to light.
