Against the end-time backdrop of a beast tide descending, ordinary college student Jiang Huai is attacked by an infected person and lies near death, when he accidentally awakens the power of the abyss-level beast 'Hundred Bones', becoming the new warden of a mysterious prison. He can transform into a skeletal giant to fight and devour beast cores to evolve. Awakener Lu Wanyin is ordered to monitor him; the two go from pretending to be a couple to fighting side by side, and their affection grows. While hiding his identity as a 'beast', Jiang Huai guards his loved one and seeks the truth about himself amid factional strife within the organization and the crisis of the beast tide.