The Great Yong Dynasty is plunged into crisis. The Retired Emperor abandons the capital and flees south, leaving the Eighth Prince, Gu Lingtian, to become a sacrificial emperor. At this desperate moment, he awakens a Population Domination System and exchanges points for modern firearms. With an iron fist, he suppresses rebellions and purges corrupt officials, takes control of the Eastern Depot and the Embroidered Uniform Guard, reinstates battle-hardened generals to defend the borders, and trains an elite personal guard armed with firearms. He also takes in orphaned children and establishes a military academy, winning the people's hearts as well as the affection of Xiao Rongyu, the daughter of a distinguished military family. With 200,000 Northern Barbarian cavalry approaching the capital and the Retired Emperor and Crown Prince secretly obstructing him from behind, can Gu Lingtian defend the capital with his formidable weapons and the courage of his people and soldiers, and forge an imperial legend?