15 years ago, a little girl named Xizhen was kidnapped and murdered. Although the police officer Oh Ching-ho (played by Kim Sang-kyung) of the Crime Squad promised Xizhen's mother (played by Uhm Jung-hwa) that the murderer would be brought to justice, after a long investigation, nothing was found. . Seeing that the prosecution period was approaching, Officer Wu made a desperate move and ended up face to face with the suspect...