Which Korean film is about a man who is imprisoned for 15 years, released and then wants vengeance?

The 2003 film "Oldboy" is about a man who is imprisoned for 15 years, released and then wants answers and vengeance. Choi Min-sik as Oh Dae-su is an obnoxious drunk who gets bailed from the police station by a friend. However, he's abducted from the street and wakes up in a cell, where he remains for the next 15 years, drugged and kept unconscious when human contact is unavoidable. He only has a television ser to keep him company. And then, suddenly released, he is invited to track down the people who kept him locked up, with a denouement that is simply stunning.

"Oldboy" is a Korean action thriller film that was co-written and directed by Park Chan-wook. It is based on the Japanese comic 'Oldboy' which was written by Garon Tsuchiya and illustrated by Nobuaki Minegishi. "Oldboy" is the second installment of 'The Vengeance Trilogy', preceded by "Sympathy for Mr. Vengeance" (2002) and followed by "Lady Vengeance" (2005). Besides Choi Min-sik, other stars in "Oldboy" include Yoo Ji-tae as Lee Woo-jin (the man behind Oh Dae-su's imprisonment) and Kang Hye-jung as Mi-do (Dae-su's love interest).

As a critical and commercial success, "Oldboy" grossed a total of $14,980,005 US dollars worldwide. After its release, the film was seen by over 3.26 million South Korean moviegoers. It was the fifth highest-grossing film of 2003 in South Korea. Also, the film was remade with the same name in 2013 in American with Spike Lee as the film's director. It star is Josh Brolin.