Modern medical student Leo transmigrated to the Ming Dynasty as a handyman. Imperial Grandson was critically ill with smallpox. Leo activated the 'Heal the World System' and saved him with immunoglobulin. With his skills and system, he cured Empress Ma, detected Crown Prince Zhu Biao's hypertension, confronted Zhu Yuanzhang, and slapped Prince of Lu. He opened a clinic with the 'Imperially Bestowed Gold Medical Plaque'. A modern soul, he ignites a medical revolution in the Great Ming Dynasty.