Mari, driven by deep impulses that surpass the ethics of being a mother, ends up having sex with her son. Tired of her mundane daily life, she begins entertaining the idea of infidelity, and taking that first step further ignites her desires—eventually leading her to cross the ultimate boundary by seducing her own son. This shocking turn of events completely transforms her relationship with him. A painful yet poignant story unfolds, as she wavers between morality and desire.