The story revolves around a forensic investigator and his team who solve complex crimes. At the same time, the main character is searching for his missing brother. "Neoreul Gieokhae" is the phrase that little Hen discovered in his father's diary. Having found his father and younger brother at a young age, he cannot shake off the guilt for something he can barely remember. Hen grows up to become a renowned crime investigator. It seems that the time has come to find the answer to the most important question...