Six years ago, Jiang Lan, the number one genius of Tianyun City, lost all his cultivation and became a good-for-nothing in everyone's eyes. Six years later, he returns from his trials, his fiancée arrives to break off the engagement, and his family faces dangers on all sides, yet no one knows that this youth in white possesses the memories and state of mind of a ten-thousand-year Great Emperor. Facing pursuit by sects, oppression by aristocratic families, and hunting by strong cultivators, Jiang Lan breaks the deadlock with his sword. What he truly wants to change is the destiny of Tianyun City being destroyed in the righteous-demonic war in his past life. To seek a sliver of survival for all living beings in the city, he seizes the Great Emperor's origin, ventures deep into the demon clan's forbidden land, and refines a saint's small world. On the day the demonic army breaks the city, Jiang Lan returns with white hair, seals tens of thousands of demons, takes the entire Tianyun City into his body, and saves countless lives.