Qin Yu, a modern-day mercenary, finds himself transported into the body of the second young master of the Prince of Qin's household in the Great Wei Dynasty. He initially intends to enjoy a carefree life, but his family faces the threat of having its noble title stripped and its officials dismissed after his father, Qin Wenyao, clashes with Emperor Wei over military expansion and disaster relief. Forced to reveal his talents, Qin Yu wins the emperor's favor with a poem and a proposal for promoting border trade, earning a position assisting Crown Prince Xiao Nan in the Eastern Palace. He takes the crown prince among the people to understand their hardships, defeats political rivals at poetry gatherings, and falls in love with Princess Xiao Rou. Using modern knowledge, he improves tea production and refines mineral salt. Together with Emperor Wei, he fights back against villains such as Fan Junliang and Bai Jiangheng, resolving a salt shortage and thwarting assassination plots. Ultimately, Qin Yu is appointed as an Imperial Censor, protects his country and its people, and marries Xiao Rou.