Gu Lingtian, a young man from the modern era, unexpectedly travels through time to the Great Yong Dynasty and immediately inherits the precarious imperial throne. The former emperor abandons the capital and flees south with all the officials, leaving the city defenseless as war approaches. With the capital deserted and the court in panic, Gu Lingtian becomes a young ruler stranded in a besieged city. Facing this desperate situation, he remains calm and decisive. Armed with extraordinary courage and the help of a mysterious opportunity, he gradually brings the Embroidered Uniform Guard and the Eastern Depot under his control, raises funds and provisions, reforms corrupt administration, and recruits talented generals. Against all expectations, he turns the tide, leads the city's people in defending their home, and rewrites the fate of a dynasty doomed to fall.