The story of Who Is the Murderer centers on the Haizhou Case from 17 years ago. Back then, young officer Leng Xiaobing encountered the major case on his very first assignment, leaving him with deep regrets. Seventeen years later, Leng Xiaobing has become an experienced detective, but he has never given up on finding the truth. When new clues emerge, he decides to reopen the case and uncover the long-buried mystery. In his search for the truth, Leng Xiaobing meets two young people closely connected to the case: Shen Yu and Xia Mu.
