Modern doctor Su Ye time-travels to become a corrupt official awaiting execution in the Hongwu era, saving the imperial grandson and the empress with the cowpox therapy, winning Zhu Yuanzhang's trust. He throws out secrets of later generations, develops firearms, establishes commercial firms and newspapers, builds the Military Training Hall, walks step by step amidst court factionalism and assassination crises, trying to rewrite the national destiny of the Great Ming with technology and institutions, and ultimately marrying Princess Anqing to lead the new army on the path to a powerful country.