Yadang: The Snitch

While serving a prison sentence for a drug crime he was falsely accused of, Lee Gang Su (Kang Ha Neul) is approached by prosecutor Koo Gwan Hui (Yoo Hai Jin) with an offer that will reduce his sentence. The catch? Gang Su will have to work as a police informant. Gang Su accepts, providing information from his drug-dealer cellmate, and the intel allows Gwan Hui to make major crime busts. Upon Gang Su's release from prison, Gwan Hui suggests that they continue their partnership, expanding their reach even further. However, narcotics detective O Sang Jae (Park Hae Jun) has noticed that his investigations keep hitting dead ends, and Gang Su somehow always seems involved. Sang Jae decides to look deeper into Gang Su and his connection to Gwan Hui – and finds that Gwan Hui's ambitions are even greater than they seem.