Lin Chuan, a modern civil service examination candidate selected for government service, travels back to the Hongwu era of the Ming Dynasty. On his way to the capital, he witnesses the ambush and attempted murder of Lin Yanzhang, a county registrar. To save his own life, he assumes Lin Yanzhang's identity and takes up the post of registrar in Jiangpu County. Facing County Magistrate Wu Huai'an, a corrupt official who pretends to be honest, and tyrannical police clerk Liu Tong, Lin Chuan uses modern administrative thinking and auditing techniques to untangle the county's chaotic accounts and win over the renowned detective Wang Jiang. He also discovers that the ambush was actually part of the real Lin Yanzhang's elaborate escape plan. By developing the docks and building a marketplace, he transforms the impoverished county into a supply hub for the capital. Using himself as bait, he turns the tables on the real Lin Yanzhang. Then, during the Crown Prince's inspection tour, he risks his life to expose corruption in disaster relief, attracting the attention of Censor Geng Qing and setting off a major upheaval in the imperial bureaucracy.