A modern office worker wakes up in another era as Wei Heng, a concubine-born son publicly disowned by his family. Armed with an extraordinary photographic memory, he turns bookkeeping into his weapon and embarks on a path to rise above his circumstances. Facing relentless pressure from his legitimate mother and underhanded obstacles in the imperial examinations, Wei Heng charges ahead, passing exam after exam and making a name for himself in the capital. Later appointed as the magistrate of Qinghe County, he uses old archives to unravel a massive case involving thirty years of missing river-construction funds, settling the old accounts of powerful families once and for all. In the end, he not only clears his late mother's name but also enters the imperial cabinet and becomes chief minister, achieving a legendary career defined by a lifetime of balancing the books and leaving no account unsettled.