Live-in Son-in-law
Gu Yan, who married into his wife's family three years ago, looks meek but is actually scheming. His wife publicly humiliates him over her infertility. He first pins his widowed mother-in-law to the bed and fucks her until she begs for mercy, then is turned on in return by his wife's half-sister with aphrodisiacs and leverage. After the half-sister seizes power, the wife joins forces with him, trading information with her body in bed, and finally exposes that the child is not of his blood. The half-sister is driven out, and the wife willingly spreads her legs, returning the position of the lady of the house and her body to him together.