After an affair forced them apart, Ryozo and Chikako reunite once more. Though their marital sex life had grown thin due to age, they had found emotional fulfillment together. One day, Ryozo's son, Yohei, returns home from studying abroad in France. He has long suspected that Chikako was responsible for his real mother's illness. Tension fills the house, and when Ryozo is away, an unexpected incident occurs—Chikako is repeatedly brought to orgasm by her young stepson's cock without her husband's knowledge. The son who violates his stepmother, the stepmother who awakens to forbidden pleasure, and the father who secretly watches over them both. Three individuals entangled in their own desires, weaving a deep narrative of infidelity and familial conflict.