An elderly man lives with his son and daughter-in-law. The son devises a plan to sell the house and obtain money, while the wife secretly indulges in an affair behind her husband's back. One day, angered by the wife's hypocritical attitude, the old man confronts her about her suspected infidelity. Fearing exposure, the wife apologizes, but the man can no longer restrain himself and spanks her buttocks. This act awakens her latent masochistic desires, giving rise to a new, forbidden relationship.