Hwang Shi Mok is an exemplary prosecutor who suffered from hypersensitivity to certain frequencies of sound. After undergoing a corrective surgery, he lost his sense of empathy and lacks of social skills. While investigating a serial murder case, he meets police lieutenant Han Yeo Jin, who assists him in solving it. As they begin to unravel the mystery behind the murders, they also discover that their efforts are being continuously foiled as expounding them will also lead to unfold the secrets about a larger scheme of corruption between the government's Public Prosecutor's Office and a private conglomerate. Written by Wikipedia