The Gangster, the Cop, the Devil — Ending Explained

The entire plot hinges on the unlikely team-up between gangster Jang Dong-soo and cop Jung Tae-seok to catch the serial killer, Kang Kyung-ho. A key twist is Dong-soo's manipulation of the investigation: he has his men use the killer's captured knife to murder a rival gang boss, Heo Sang-do, thus framing the killer and solving his own turf war problem. This act deepens the moral ambiguity and creates friction with Tae-seok.

The climax sees Dong-soo capture the killer, intending to torture and kill him. However, Tae-seok intervenes, crashing his car into the hideout and arresting Kyung-ho to ensure legal justice. The final, and most significant, twist comes during the trial. With no definitive evidence to secure a death sentence, Tae-seok is forced to ask Dong-soo to testify as the sole surviving victim. Dong-soo agrees, but only on an unrevealed condition. In court, Dong-soo's testimony is decisive, and he points to a stab wound on the killer's chest that he himself inflicted, which clinches the conviction. Kyung-ho is sentenced to death, but Dong-soo is also arrested for his own admitted crimes.

The film's masterstroke is revealed in the final scene: Dong-soo's condition was that he be incarcerated in the same prison as the killer. As Dong-soo enters the prison, he sees Kyung-ho, whose signature smirk of invincibility vanishes, replaced by terror. Dong-soo approaches him with a rope and a smile, making it clear that while the cop achieved his legal justice, the gangster will now have his personal revenge, fulfilling both of their initial goals in the most cynical way possible.

One alternative reading of the film focuses on the title itself. While the roles of 'Gangster', 'Cop', and 'Devil' are explicitly assigned to the three main characters, their actions suggest these labels are interchangeable. The gangster dispenses a form of justice, the cop acts with criminal brutality, and the true 'devil' might be the corrupt system that allows such chaos to flourish. The film can be interpreted not as a story of three distinct figures, but as an allegory for the different faces of evil that society harbors. The ending can also be read less as a victory for the gangster and more as a condemnation of a justice system so flawed that the only satisfying conclusion must happen outside its walls, in the dark confines of a prison shower, perpetuating a cycle of violence.