I Saw the Devil (2010) http://www.imdb.com/title/tt1588170/
This import from Korea is about a secret agent that tracks down the serial killer that killed his fiancee. Instead of killing him, the agent catches him, beats the crap out of him, releases him, then tracks him down again -- all to extend the serial killer's suffering, to make him pay for what he did.
As a Korean film all dialog is subtitled. That doesn't detract from the film in any way- one quickly gets used to reading dialog and watching at the same time. Most action-laden scenes don't have dialog anyhow. There's plenty of time to not miss anything, unless you can't stomach the scene.
If you've seen "Oldboy" then you'll recognize that film's title character actor Min-sik Choi, he plays the serial killer in this one. Quite effectively too, he plays him as a generally emotionless psychopath with sociopathic tendencies.
This movie is graphically violent, bloody, disturbing. The makeup and effects are top notch. Heck the whole production, from settings, camera work, fight scenes and sound are top notch. The story keeps you riveted, though the more squeamish will probably avert eyes at some parts. The film clocks in at 2 hours 21 minutes but it certainly doesn't feel that long. The pacing of the film gives you time to start relaxing after some parts, but not enough to bore, and progresses well.
The only complaint I voiced was about the agent's tendency to drive against the direction of traffic. I can see maybe once because of the immediacy of that situation, but this guy seemed to do it quite a bit.
What makes the story and film work is the emotional component - the agent is driven by his grief and it shows, finally breaking through at the end. However the film ends a little further down field on the 'revenge-crazy' scale than I'd anticipated it would. Even if you've been numbed by everything up to that point it takes it one step further. But that's probably part of the message, the agent's becoming a monster to take out a monster.
As for the 'hero' of the film being an agent I'm sure it's to explain why he's highly trained in hand-to-hand combat and has access to some spy tech.
The characters feel real. This film is on a whole different level than American revenge/torture flicks that are similar to the "I Spit on Your Grave" or "The Last House on the Left" remakes, for example. Even though they may be similar in graphic violence and gore, ISoYG and TLHotL characters are rather two dimensional in comparison to "I Saw the Devil" character portrayal. Considering that IStD is subtitled, I thought it rather impressive to overcome that language barrier and be that effective. Perhaps the quality of character development and the acting in this film made me less mindful of the graphic violence - it just didn't have that 'here is an absurd violent graphic revenge act for the sake of violent graphic revenge act' feel to it.
A solid film, but I'd only recommend it to people who can handle grisly fare.