Yuko is a busy housewife juggling work and childcare. One day, suffering from chronic shoulder pain, she finds a suspicious flyer for an in-home massage service in her mailbox. Curious, she calls and schedules a session. The therapist who arrives appears kind and professional, but harbors a hidden agenda. Using oil, he begins a sensual body treatment, slowly breaking down Yuko's resistance with his lewd techniques. Before long, she succumbs to pleasure—and even draws her son into the forbidden act, pulling the entire family into a web of incestuous desire.