As Emperor Quinn of Great Yan struggles to choose an heir, he secretly visits Quentin, his supposedly simple-minded illegitimate son living outside the palace. But Quentin is no fool. He is actually a modern-day transmigrator. He mistakes Quinn for a merchant, urges him to rebel, and offers him the design for a curved-shaft plow. Quentin's talent soon comes to light. He partners with Maggie in the soap business, wins over Chancellor Charles, and later joins the Northern Army. There, he improves iron-smelting and horse gear, develops gunpowder and a powerful crossbow, and defeats the nomads. Back at court, Quentin uses papermaking and printing to break the noble clans' hold over knowledge. When they rebel to bring him down, their uprising only helps him rise higher. In the end, the prince they once dismissed becomes crown prince and receives an imperial decree to marry Maggie.
