Yi-eon, the eldest son of a family that was destroyed due to treason, arrives at a mountain lodge while running away with his nephew Yeon-o, the only heir to the family. However, this place is the gateway to hell for Yi-eon... In order to save his nephew, Yi-eon becomes a toy as the lodge owner demands, but his nephew catches him in his ugly state that he never wanted to be found out about, and he ends up facing a cruel fate where he is even teased by his nephew. However, whenever he feels that there are still traces of a strange man on his uncle's body, Yi-eon becomes more violent, and eventually demands to be called 'Master'...! Should he live as a human, or give in to his instincts? Yi-eon gradually faces the fact that he is becoming less and less than human, like livestock.