A brother living with his fifty-year-old stepmother gradually gives in to lewd fantasies in their daily life. When she goes out, he checks her underwear in the washing machine or sniffs her freshly discarded panties. He secretly films her while she bathes—erotic acts that have become routine at home. Returning late at night from her job at a snack bar, the stepmother's sensuality intensifies. Her G-cup breasts and glimpses of flashy lingerie between her thighs drive her sons wild with arousal. Obsessed with their stepmother's body, the brothers eventually progress toward incestuous sex.