On their daughter Rio's birthday, Erina receives a desperate video call—Rio is trapped inside a scorching car under the blazing sun. While Erina frantically searches for her, her husband Seiichi is enjoying a day at an amusement park with his late best friend's wife, Serika, and her son. As everyone hides the truth, Erina races against time with the help of surgeon Jin Kiritani. They find Rio inside Serika's car—but it's too late. Heartbroken after reading Rio's diary, Erina decides to end her loveless marriage and seek justice.
