The depletion of Xuanjing caused an imbalance in the four realms. Lingxi, a doctor in the mortal realm, was actually the young master of Xuanjingyuan, and the "Heart of the Realm" that maintained balance was sealed in his body. On a rainy night, she rescued Mo Yuan, the God of War in the High Heaven Realm, who was seriously injured. The two secretly fell in love, but lost their memory and turned against each other because of accidentally eating Forgetwort. She also didn't know that Mo Yuan was actually a hybrid between a fairy and a demon.
In order to seize the world heart and dominate, Lingxiao Immortal Lord falsely accused Mo Yuan of being a demon and forced him to awaken the demon blood. After awakening his power, Lingxi resisted the Immortal Lord's plunder of the Xuan Crystal while struggling between "protecting the world heart" and "protecting Mo Yuan".
In the end, the two resolved their misunderstandings about identity and memory, and joined forces with the Burning Demon Territory rebels and Xuan Jingyuan's old tribe to fight against the Immortal Lord, using the power of the fusion of the world's heart and demon blood to repair the four realms. Mo Yuan abandons his identity as a fairy and demon and accompanies Ling tide to retreat to the mortal world. The foreshadowing of the reincarnation of the heart of the world at the end hints at new waves in the four realms.
