Criminal investigator Misaki attempts to rescue Yilin, an international student held captive by a yakuza group, but fails and ends up causing her death. Traumatized by the incident, Misaki is assigned to protect Yilin's mother, Lin'en, and her sister, Feifei, who have arrived in Japan. However, while visiting the crime scene to lay flowers, Lin'en is shot and killed. Under intense pressure, Misaki must confront the next crisis head-on.