Ye Xuan accidentally transmigrated into the beast-taming world and became the illegitimate son of the Ye family, only to be thrown together by his brothers into the Gu-raising arena on a desolate island in the Nether Demon Mansion. Faced with cruel trials and pursuit by powerful enemies, he awakened dual talents and, relying on the Demon-Refining Pot, cultivated the inconspicuous Night-Slaying Mantis into an endlessly evolving killing blade. With the assistance of healing-type maiden Sun Yutang and other partners, he moved from survival to rebellion, vowing to fight his way out of the desolate island and demand justice from the family. However, the clues to his mother's disappearance led him toward an even deeper conspiracy within the Nether Demon Mansion.