Oldboy
I was audibly yelling NO multiple times during the climax.
This is an insane movie. Oh Dae-su is imprisoned for a reason we don't know of for 15 years in absolute isolation and torture. He is released suddenly and hangs out with Mi-do. We are exposed to amazing fight scenes and intensity that is matched by the likes of Quinton Tarantino and John Woo, along with expert acting and balanced direction, especially the cinematography and masterful between action and drama. This plays on revenge-fantasy by upending its conventions of grandeur and post-prosperity, showing that it can be extreme and diabolical evil that is overwhelming, thorough and fascinating.
The climax ties it all together in a slightly obvious twist, but only if you're a massive mystery nut and expecting a crazy ending. The twist still had me gasp and yell, Jin-woo is such a sleazy evil antagonist with some of the most fucked up motives I have ever seen in a movie. He is easily one of my most hated movie villains because wow, was he fucked up.
This is an action-thriller from Korea with a twist, conspiracy and mystery, you have to see.