Lin Yuan, a modern civil engineer, accidentally falls from a building and finds his soul transmigrated into Zhu Di, the Prince of Yan, in the early Ming dynasty. He unexpectedly activates the Heavenly Craftsmanship System. Facing internal turmoil and external threats from the start, with Northern Yuan cavalry at the border, border generals withholding provisions and pay, and the Three Guards scattered and weak, he turns the tide using a thousand years of infrastructure and military engineering knowledge. He doubles crop yields with ridge farming, builds blast furnaces to produce fine steel, and creates powerful repeating crossbows that strike fear across the northern frontier. From an idle prince, he gradually establishes himself as the ruler of Beiping. The virtuous Princess Consort Xu Miaoyun goes from sensing something unusual about him to entrusting him with her heart, taking charge of internal affairs as they weather the crisis together. In the final years of the Hongwu reign, undercurrents stir at court, and a covert struggle over military power on the northern frontier and the fate of the empire quietly begins.