Ko, a corrupt detective grappling with the death of his mother, finds himself in a precarious situation as his squad is under investigation by internal affairs for bribery. After his mother's funeral, while driving to the station, he inadvertently hits a homeless man, killing him. Terrified of facing manslaughter charges due to his intoxication, Ko opts not to report the accident and instead conceals the body in his car trunk—barely avoiding detection from a passing patrol car. With a grim decision made, he returns to the funeral, hiding the body inside his mother's coffin, only to discover later that the man's cell phone was left behind, still in the coffin. Fortunately for Ko, a lieutenant named Park cancels the internal investigations just days later.
Assigned to track down a wanted murderer named Lee, whom Ko recognizes as the very homeless man he killed, the squad's investigations lead them to Lee's hideout. While searching, they encounter a police officer digging into a hit-and-run case. To their dismay, it becomes apparent that Lee’s hideout is alarmingly close to the collision scene, with a traffic camera recording the entire event. Upon examining the grainy footage, the resemblance of the colliding car to Ko's own vehicle becomes undeniable. Further complicating matters, the triangulation of Lee's cell phone indicates activity near Ko's mother's grave.
In a twist, it is revealed that Lieutenant Park, who had passed by moments after the incident, is aware of the collision, but instead of reporting Ko, he opts for a more sinister route—blackmailing him for possession of the body. Ko, in a panic, excavates the coffin to examine Lee's body, uncovering bullet wounds that hint at foul play. The tension escalates as Lee's phone receives a call from a criminal whom Ko tracks down. This criminal spills the details about a significant theft of confiscated cocaine by Park. It surfaces that Lee had snatched the key to a private vault containing Park's ill-gotten gains, just before he was shot during his escape from Park’s pursuit.
Frantically, Ko makes his way back to the grave site to find the key, but his effort is thwarted when he is apprehended by his own subordinate, who had been investigating the damage to Ko's vehicle. Tragedy strikes when Park resorts to lethal measures, using a crane to drop a shipping container on Ko's subordinate's car, ensuring silence.
Ko, feeling cornered, contemplates confessing his crimes but is held hostage by Park's threats against his family. Unwilling to let anything happen to them, Ko devises a plan: he prepares an explosive device and places it within Lee's body. Presenting the corpse to Park, he triggers the explosion, sending Park's vehicle careening off a bridge into a lake. When Ko returns home, ready to confront his past, he is blindsided by Park, who somehow survived the blast. In a chaotic struggle, Park unwittingly shoots himself while trying to reclaim his weapon from a fallen shelf.
Ultimately, senior police officials decide to obscure both Park's and Ko's misdeeds to save their own reputations. Choosing to step back from his position, Ko uses the key from Lee's body to access Park's secret vault, revealing an astounding cache of cash that exceeds his wildest expectations.
