Lin Mo, a modern-day overworked office worker, dies suddenly from working overtime and transmigrates into the lowest-ranking tomb-guarding laborer at the imperial mausoleum of the Great Yong dynasty. From the very beginning, he is about to be executed as a scapegoat. At this critical moment, the Black Dragon Token he carries close to his body unexpectedly comes to light, astonishingly causing the entire Imperial Guard to kneel in reverence. It turns out to be a token bestowed by the late emperor upon the founding nobility. Lin Mo is the son of a reclusive nobleman whom the emperor has desperately searched for over the past ten years. From then on, Lin Mo joins the Imperial Guard, exposes conspiracies, battles powerful ministers, and solves difficult problems concerning the court and people's livelihoods, repeatedly foiling the schemes of princes and aristocratic clans. As the mysteries surrounding his identity gradually unravel, father and son shed their hidden identities and stir up a storm in the imperial court. In the end, having accomplished their mission, they retire from public life and live in seclusion amid mountains and rivers.