Late one night, a bizarre murder occurred in the old town of a coastal town. Guan Jingtang, a well-known local elder, died tragically in his villa. Criminal police captain An Ping (Han Dong) was ordered to investigate, and Shang Jie (Qu Jingjing), a top student in the provincial department, volunteered to investigate. The two cooperated fully and launched a meticulous investigation. However, as the investigation continued to deepen, various contradictory doubts emerged one after another, coupled with the huge amount of cash that disappeared, the familiar woman in red, the blood-red flower pattern, and the intricate interpersonal relationships of the Guan family, making the case more confusing. Not only that, murders continued to occur one after another, and the deceased were all closely related to Guan Jingtang. An Ping and Shang Jie withstood the huge pressure and investigated from the source, turning over an old case, and An Ping's master, who was also Shang Jie's father, died because of that case. Finally, Anping unravels the mystery, uncovers the real culprit whose mind has been twisted for a long time, and brings him to justice. Shang Jie also walks out of the shadows, untangling the knot that has troubled her for many years, and decides to stay and inherit her father's legacy, fighting side by side with Anping.