Stranger

In the first season, Hwang Si-mok (Cho Seung-woo) is an exemplary prosecutor who suffers from hypersensitivity to certain sound frequencies. After undergoing corrective surgery, he lost his sense of empathy and lacks social skills. While investigating a murder, he meets Police Lieutenant Han Yeo-jin (Bae Doona), who assists his efforts to solve the case. As they begin to unravel the mystery behind the murder, they find that their efforts are continually being obstructed by participants in a major corruption conspiracy between the Prosecutors' Office and a private chaebol (conglomerate). In the second season, set two years later, a dispute arises between the Prosecutors' Office and the National Police Agency, with the former wanting control over all investigative proceedings while the latter seeks autonomous authority to conduct investigations. In the midst of their respective agencies' conflict, Hwang Si-mok and Han Yeo-jin team up to conduct their own independent investigation of a concealed case.