Ning Yechen, the former supreme ruler of the Demon Realm, lives in seclusion in the human world. By chance, he forms a bond with Luo Ruying, the female emperor of the Immortal Realm, and they have a daughter together. Five years later, Luo Ruying takes their daughter to find her husband, only to be hunted down by the villain Changjue. To protect his wife and daughter, Ning Yechen reveals his true power as the Demon Venerable, storms the Immortal Realm, intimidates the gods, and rallies the forces of the Demon Realm to fight their enemies. Along the way, he uncovers the truth behind the pursuit, defeats Changjue, and reclaims the immortal bone, resolving the divide between immortals and demons. In the end, he joins hands with Luo Ruying to unite the Three Realms and usher in a golden age of harmony between immortals and demons.