Initially, I found myself struggling to grasp the premise. The story centers on "Lee Kang-su" (played by Kang Ha-neul), a bold and self-assured young man who obtains information about drug traffickers, sharing it with law enforcement in exchange for personal gain and reduced sentences for those cooperating as informants. However, their investigations increasingly run into political roadblocks, quickly creating complications for this “Yadang.” He becomes a casualty of his former protector, the ambitious prosecutor "Ku Gwen-hee" (portrayed by Yoo Hae-jin), who subjects him to excessive doses of blue methadone, disorienting him completely. Following his release, he joins forces with a similarly exploited ex-police captain, "Oh Sang-jae" (played by Park Hae-joon), and a young actress (Chae Won-bin) whose career was destroyed when she was also exposed to the addictive substance and subsequently used as an escort by someone connected to the highest levels of power – all while an election approaches. Once the narrative gains momentum, it emerges as a fairly diverting, though not consistently believable, exploration of profitable drug trafficking and political maneuvering in a South Korea seemingly committed to eradicating crime, regardless of the risks involved. It's a raw, occasionally sleazy film featuring strong performances from both male leads, with Kang Hae-neul displaying particular energy. The two-hour runtime includes ample action sequences, and the ending bears resemblance to “The Sting” (1973), as retribution proves limitless. I’d recommend seeing it.

Source on TMDB