After the Kingdom of Chu is defeated in war, its prince, Ying Yuan, is sent to Great Yan as a hostage. Amid a torrential downpour, he would rather die than write a letter of surrender. However, the ruthless and unpredictable Grand Princess Ji Ruxue takes him in as her personal sword-bearing slave. After awakening the Imperial Ambition System, he appears humble and obedient on the surface while secretly awakening his elite death squad, weaving an intelligence network, seizing the Tiger Tally, and taking control of military power. He rises step by step by exploiting the Grand Princess's trust. She believes she has tamed a loyal dog, unaware that this patient and calculating hostage is plotting to ascend the throne. As an ambiguous master-disciple relationship, the ancient enmity between the two kingdoms, and rebellious vassal princes all draw near, who will fall into whose game first?