A man is mysteriously imprisoned for 15 years and begins his journey to uncover the truth and seek revenge upon release.

"Oldboy" follows ordinary office worker Oh Dae-su (played by Choi Min-sik) who is kidnapped and imprisoned in a private jail for 15 years. During his confinement, he learns through TV that his wife was murdered and he became a suspect in the case. After several failed suicide attempts, Oh Dae-su vows to clear his name and begins preparing physically for escape.

Upon his unexpected release after 15 years, he embarks on a quest for truth. He seeks help from young chef Mido (played by Kang Hye-jung), gradually uncovering a twisted story of betrayal, revenge, and taboos. He traces a young woman named Yu-ran Lee (played by Yoon Jeong-hee) who has a complex connection to his past and imprisonment.

As Oh Dae-su nears the truth, he finally confronts the man behind his ordeal - Lee Woo-jin (played by Yoo Ji-tae), a former schoolmate with a deep personal grudge. The film reveals a shocking truth that forces Oh Dae-su to face painful choices and confront his own past.

'Oldboy' is the second installment of Park Chan-wook's "Revenge Trilogy," which also includes 'The Revenge' (2002) and 'Sympathy for Lady Vengeance' (2005). These three films collectively explore various dimensions of revenge and moral dilemmas.

To portray the character Oh Dae-su, Choi Min-sik underwent an astonishing physical transformation. In the film's first half, he portrays an ordinary office worker, while the latter half showcases his muscular physique and strength after years of imprisonment and training. It's reported that Choi Min-sik gained 10kg for the role and later lost 20kg, earning widespread praise for his dedication.

The iconic corridor fight scene is a technical masterpiece. This three-minute single-take action sequence, with no cuts, is a collaboration between director Park Chan-wook and cinematographer Chung Chung-hoon. It reportedly took three days to film, with Choi Min-sik performing most of the stunts himself, demonstrating extraordinary professionalism.

'Oldboy' was originally adapted from a Japanese manga of the same name, but Park Chan-wook significantly reworked the story, adding psychological depth and cultural elements, transforming it into a uniquely Korean revenge masterpiece. The film won the Jury Prize at the 2004 Cannes Film Festival, establishing Park Chan-wook's international reputation.