The father's new wife is just as beautiful as the son, and she becomes an object of desire for the son. The son decides that things can't continue like this and decides to leave home. The family goes on a trip to a hot spring for the last time. The father gets drunk and falls asleep. Alone with the beautiful stepmother... the son can't resist and begins to desire his mother. Though confused, the mother is unable to suppress her son's passion and accepts their one-night love. A forbidden incest story between a stepmother and her son, who lose themselves in the pleasure of a sense of guilt and the young, erect penis.