Wei Wuxian remains in the Cloud Recesses as the mad maniac from the Lanling Jin Clan, while his old cultivation classmate, Lan Wangji, hunts for information concerning the demonic severed arm they have in prison. With an outpouring of evil energy emerging from the arm, the two are compelled to collaborate in order to contain it. However, the demonic arm is not the only evil power in the area, and when spiritual tensions increase in the Gusu Lan Clan's mountains, it is up to the two of them to try to restore natural order. More light is being revealed on Wei Wuxian's plunge towards the path of demonic cultivation as the narrative of his fall from grace proceeds.