Miki Sunohara has been married to her husband and his son for five years, maintaining a good relationship with her stepson. One day, while masturbating on the phone with her lover, she is caught by her stepson. Learning from their conversation that her marriage was only for money, the son blackmails Miki and demands sexual favors. Starting with blowjobs, he begins making increasingly intense demands, relentlessly toying with Miki's body. This series of events unravels the family structure, pulling Miki into a whirlpool of desire.