Modern youth Zhou Qingyan and cousin Lin Jingye simultaneously fall into a spacetime rift, one cultivates bitterly for ten thousand years to become an immortal emperor, the other ascends to demon emperor in a hundred years. Learning that a thousand years in the other world equals one day on Earth, the two decide to sacrifice the Heavenly Dao and gather the origin of the three realms to go home, only to discover behind the door of return lies a shocking conspiracy devouring the two worlds. The brothers must make the ultimate choice.