Unemployed and addicted to gambling, the father-in-law lives off his son's newlywed household, neglecting work and staying shut indoors. Resentful toward his daughter-in-law, he one day stumbles upon a massage parlor where he discovers her secretly working. Learning of her hidden life, he begins to exert control over her. Drawn to his large cock, she starts visiting his room every night instead of her husband's. The relationship between father-in-law and daughter-in-law takes a dark, twisted turn, evolving into something entirely different from before.