"Oldboy" (2003) follows Oh Dae-su, a man imprisoned without explanation for fifteen years, who is suddenly released and given five days to find out who locked him away and why. Director Park Chan-wook built the film around a mystery that only resolves in its final act, when the truth about Dae-su's captor reframes everything that came before as a carefully engineered act of revenge. The South Korean thriller, based on a Japanese manga of the same name, follows Dae-su's search for his jailer and his relationship with a young sushi chef named Mi-do, who helps him investigate. The ending reveals that his imprisonment was punishment for a rumor he spread in high school, and that his tormentor, Lee Woo-jin, has spent years orchestrating a revenge that implicates Dae-su in something far worse than he realizes.
Table of Contents
- What Happens at the Start of the Film
- How Dae-su Investigates and What He Finds
- Who Imprisoned Dae-su and Why
- The Twist With Mi-do and the Ending Explained
- What the Ending Means
- Frequently Asked Questions
What Happens at the Start of the Film
Oh Dae-su is a drunk, obnoxious businessman who gets picked up by police on his daughter's birthday for disorderly conduct. After his friend bails him out, he vanishes from a street corner and wakes up locked in a private room disguised as a cheap hotel. He has no idea who has taken him or why. He stays in that room for fifteen years, fed only fried dumplings and given a television as his sole connection to the outside world.
Through news broadcasts, he learns his wife has been murdered and he is the prime suspect, which cuts him off from any thought of going back to his old life even if he escapes. He trains his body, plans an escape through the wall, and rehearses revenge in his head for over a decade. Just as he is about to break through the wall, he is suddenly released, placed on a rooftop in a trunk, dressed in a new suit, and given money and a cell phone. The captor, still unidentified, calls him and sets a challenge: find out why he was locked up within five days.
How Dae-su Investigates and What He Finds
Soon after his release, Dae-su meets Mi-do, a young sushi chef, at her restaurant. She takes him in despite his strange behavior, and the two grow close as he begins piecing together clues his captor leaves for him, including a dumpling box that leads him to the restaurant that supplied his prison food for fifteen years. Using the restaurant's delivery records, Dae-su traces his imprisonment to a private facility run for hire, which narrows down the window of time he was held and who could have arranged it.
He also tracks down the man who physically guarded him, torturing him for information that eventually points toward a connection from his own past rather than a stranger. The investigation forces Dae-su to confront that his imprisonment wasn't random. His captor has resources, patience, and a personal motive, which means the answer lies somewhere in Dae-su's own history, not in organized crime or mistaken identity as he first assumes.
Who Imprisoned Dae-su and Why
The man behind Dae-su's imprisonment is Lee Woo-jin, a wealthy executive Dae-su knew briefly in high school. Years earlier, Dae-su witnessed Woo-jin having an incestuous relationship with his sister and, not realizing the two were already a couple with real feelings for each other, spread the rumor around school. The humiliation led Woo-jin's sister to take her own life. Woo-jin blamed Dae-su entirely for her death and spent years building the wealth and planning needed to destroy him just as thoroughly.
The fifteen-year imprisonment was only the first phase. Woo-jin also used hypnosis, administered by a hypnotist working on his behalf, to manipulate Dae-su's emotions and memory without his knowledge. The challenge Woo-jin poses after release isn't just to identify him. It's to figure out why Dae-su was targeted at all, since Woo-jin wants Dae-su to understand and feel the same kind of guilt and loss that drove his sister to die, not merely to suffer physically.
The Twist With Mi-do and the Ending Explained
The film's central twist is that Mi-do is Dae-su's own daughter, Sa-rang, though neither of them knows it during their relationship. Woo-jin orchestrated their meeting and used hypnosis to suppress the memories that would let Dae-su recognize her, engineering a romantic and sexual relationship between father and daughter as the ultimate form of revenge. When Woo-jin reveals this to Dae-su near the end, he threatens to tell Mi-do the truth unless Dae-su performs a humiliating act: he cuts out his own tongue, using the same method he once used to try to apologize to Woo-jin's sister, as proof of submission and remorse.
Woo-jin, in turn, is satisfied enough by Dae-su's suffering that he takes his own life immediately afterward, having achieved the symmetry he wanted between Dae-su's guilt and his sister's death. In the final scene, Dae-su hires the same hypnotist Woo-jin used, asking her to erase his memory of the incest revelation so he can continue his life with Mi-do without the knowledge destroying him. The hypnotist performs the session, and the last shot shows Dae-su reunited with Mi-do in the snow, his expression caught between relief and residual anguish, leaving it deliberately ambiguous whether the hypnosis fully worked.
What the Ending Means
The ending works as a commentary on the cost of revenge for everyone involved, not just the person being punished. Woo-jin gets the vengeance he spent his life building, but it kills him anyway, suggesting that his years of planning never actually resolved his own grief over his sister.
Dae-su's choice to erase his memory rather than face the truth reflects the film's broader argument that some knowledge is unbearable regardless of how it was obtained. Park Chan-wook leaves the final shot unresolved on purpose: the audience sees Dae-su smiling, but also sees him recoil briefly when the hypnotist says the trigger phrase, implying the memory may resurface, as if real trauma can be suppressed but not fully destroyed.
Frequently Asked Questions
Is Oldboy (2003) based on a book?
It's based on a Japanese manga of the same name by Garon Tsuchiya and Nobuaki Minegishi, though the film's ending and central twist differ significantly from the source material.
Why does Dae-su cut out his tongue?
He mirrors the act he once used as a child to try to apologize, offering it to Woo-jin as proof of total submission and remorse in exchange for Woo-jin's silence about the incest revelation involving Mi-do.
Does Dae-su actually forget the truth at the end?
The film leaves it ambiguous. He asks the hypnotist to erase the memory and appears at peace in the final scene, but a brief flicker of distress when she speaks the trigger phrase suggests the memory may not be fully gone.