Ko, a corrupt detective whose mother just passed away, finds his team under internal affairs scrutiny for bribery. On the day of the funeral, as he drives away from the ceremony, he collides with a homeless man and, because he is intoxicated, chooses not to involve the police. He hides the body in his car trunk just as a patrol passes, then returns to the funeral and stashes the corpse inside his mother’s coffin—only to later discover that the man’s cell phone remains inside the coffin with him. A few days pass, and to everyone’s relief, the internal affairs investigation is quietly closed by a lieutenant named Park.
The squad is reassigned to track down a wanted killer named Lee, who Ko recognizes as the homeless man he just killed in the accident. While they search Lee’s hideout, they encounter another police officer investigating a hit-and-run, and they learn that Lee’s location sits right beside the crash site, visible from a traffic camera. The low-quality footage suggests the same model of car involved in the collision may be tied to Ko. A phone triangulation places Lee’s last activity near Ko’s mother’s grave, deepening the mystery.
It’s revealed that the patrol driver who drove past Ko after the fatal incident was Park—the same lieutenant who quietly shut down the investigation into Ko’s team. Park doesn’t know where the body is, but he uses the knowledge to coerce Ko for control of it. Ko digs up the coffin and finds Lee’s body riddled with bullets. Lee’s phone receives a call from a fellow criminal, which Ko presses to learn more. The criminal reveals that Park stole a large cache of cocaine and hid the profits in a private vault; Lee, in turn, stole the key and fled. Park had shot Lee and was pursuing him when Ko’s car collided with him. When Ko asks about the key, he learns that anything truly important stayed with Lee on his person.
Ko heads back to the grave site and locates the key, only to be abruptly arrested by a subordinate who tails him after noticing Ko’s car damage around the time of Lee’s death. The subordinate is killed when Park uses a crane to drop a shipping container onto his car. Ko plans to go public with Park’s crimes, and even contemplates surrender, but Park threatens Ko’s sister and daughter to force silence. In a desperate move, Ko steals an explosive from the police basement, implants it into Lee’s body, and hands the corpse to Park, detonating the charge to blow Park’s van off a bridge into a lake.
Returning to his apartment, Ko readies himself to report everything, but Park, who somehow survived the blast, stages a confrontation. In a chaotic moment, Park accidentally shoots himself while attempting to dislodge a revolver from a toppled bookshelf. With officials eager to protect reputations, a cover-up of Park’s and Ko’s crimes begins to harden. Ko, choosing to resign, uses Lee’s bodyKeys to infiltrate Park’s private vault and discovers an enormous cache of cash—far beyond anything he had imagined—leaving him to confront a new, darker reality about power, profit, and the cost of truth.
