The plot of "Who is the Murderer" is centered on the "Haizhou Case" 17 years ago. The young police officer Leng Xiaobing encountered this major case on his first mission, leaving him with deep regrets. Seventeen years later, Leng Xiaobing has become an experienced criminal policeman, and he has never given up his belief in finding the truth. When new clues emerged, Leng Xiaobing decided to re-investigate the case and uncover the long-standing mystery. In the process of searching for the truth, Leng Xiaobing met two young people closely related to the case-Shen Yu and Xia Mu.
