[Warning: The following contains major spoilers for the film Oldboy (in fact, it reveals the whole plot) so don't read unless you've seen it]
A deleted scene from Oldboy
Revenge-obsessed villain (ROV) and evil henchman (EH) are seen sitting in ROV's office.
ROV: Remember that guy who spread the rumour that I was doing my sister in school? The one that made her commit suicide?
EH: Yeah, I do. (To himself:) You dirty bastard...
ROV: Well, I want to get him for that. I settle his hash alright.
EH: So what d'ye want me to do? Get a few of the lads, drive the guy down to the warehouse, and torture the shit out of him? That'll learn him!
ROV (shaking his head): No, no, no. That's too simple. I want his family to suffer too.
EH (getting visibly excited): We'll kidnap his kid and kill her in front of him, then torture him too! That'll really learn him!
ROV: Oh, EH. (Shakes head ruefully) You just don't see the big picture ... Here's what we'll do. We'll kidnap the guy and toss him into a room for 15 years. Then we'll hypnotise him so that when he gets out, he'll sleep with his own daughter. But we won't tell him why he's been shut away for 15 years, so he has to find out for himself, like a detective. Then, when he's discovered everything, he'll be destroyed and I'll shoot myself! Brilliant, eh?
EH: (Stunned silence.)
ROV (imperiously): Well, what do you think!
EH: Oh, it's fantastic, pure genius! There's no way I'd ever think up anything like that. So we'll lock the guy in a room for 15 years - wait, won't he be horribly weakened and disturbed after 15 years of solitary confinement? Like, if you let him out on the street you'll be lucky if he makes it ten feet before collapsing. He'll need months in hospital and a team of psychiatrists to get him over it!
ROV: He'll be fine. We'll keep an eye on him while he's locked up.
EH: But 15 years in a single room with no sunlight and eating nothing but dumplings will destroy his constitution. An infection, or even a single dodgy dumpling, could kill him!
ROV: He's strong; he'll be fine!
EH: But when he gets out, even if he's not horribly weakened and psychologically unable to function, he'll be incredibly disorientated. What if he gets run over by a truck, or falls down a flight of stairs, or gets killed by a mugger? That's 15 years of planning down the toilet, isn't it?
ROV: I'm getting a bit tired of all these objections.
EH: And it'll cost you a fortune. You'll have to pay for his kid's upbringing and to keep this guy locked up (and what if she dies before the 15 years are up? Or turns out to be a lesbian? What if he's impotent after all that time?) And what if the guy's too thick to figure out the mystery? You'll just have to go in and tell him, which'll spoil the mood. What if you die before he gets out? You going to leave him a letter?
ROV: Shut up.
EH: Isn't it an incredibly roundabout way of getting revenge? Why not just shoot the guy? I mean, the guy gets out after 15 years and you tell him he's just slept with his daughter, right. And he could say: "Hell, that kid wasn't mine; my wife had an affair with the postman. Me and the wife had a long talk, and decided to keep the baby and raise it as our own." Or he could say: "Oh, that's horrible, but after being locked up for 15 years I'm not really bothered." And when you go on about how awful what he's done is, he'll just say "Oh great, lectures on morality from the guy who slept with his own sister! Pot and kettle, huh?" You really don't know how he'll react after all that time.
ROV: Shut up!
EH: Alright, alright; you're the boss. (Stands up to leave, muttering to himself:) Oddball...
ROV (puts feet up on his desk, and opens a box of Blue Dragon dumplings): Ah, dumplings! The perfect side dish for .... revenge! Now to listen to the radio. (Turns on the radio, which plays the following song. A frown crosses his face...)