Su Lin, a young girl, was neglected by her parents since she was a child and grew up in a poor and difficult environment, but she always studied hard and looked forward to the future. Su Lin worked hard at speaking and won the role of the Little Mermaid in the English recital play, which made her classmate Ma Na jealous. During a fierce conflict, she accidentally fell into an underground pipe, and her life or death was unknown. At this time, the "case of three female corpses" in the city's underground river was also exposed to public view. In an instant, the investigation of the case was closely intertwined with Su Lin's fate. Retired police officer, Gu Hao, and Jiang Ting, a girl from the same school who met unexpectedly, have always been concerned about Su Lin's situation.
