Is it possible to break a monster incapable of feeling pain or fear? One man sets out to try after losing his fiancé to a demented serial killer and rapist. What he begins to find out is that his quest for revenge could change him forever. Turning him into the very thing he seeks to destroy. It's a moral quandary we've seen before, but rarely at this level of unflinching brutality. Make no mistake, you will most definitely see the devil because this movie is a trip through hell. Kim Jee-woon shows us the darkest, most unsafe side of the world. Secluded areas where a seemingly endless array of psychopaths own the night and collect as many victims as possible. The content is incredibly graphic and I'm not just talking about the violence. Torture and gore are certainly the foremost vices the sick predators of this film like to engage in, but they have a tendency to explore other disturbing perversions as well. Such as sexual assault, cannibalism, and even pedophilia. It's a dark and grotesque movie for sure, but there's a certain absurdity to it. While never an easy watch, a pitch black sense of humor keeps the harsh content from ever becoming too much to handle. At least for the more seasoned viewer. I did notice where it went too far with the joke on one occasion. The almost cartoonish mishandling of a severed head by a member of a forensics team that causes it to come spilling out for all to see was in bad taste. For the most part though these more comedic moments do a lot to a touch of lightness to what could have otherwise been an overbearingly revolting experience. The two lead performances are incredible. Lee Byung-hun is a sympathetic protagonist even at his lowest point because of the emotion he brings to the character. Choi Min-sik is hands down one of the most terrifying serial killers in all of cinema. He's menacing, dangerous, and creepy. They're the perfect rivals. Both fundamentally broken in different ways with unrelenting natures destined to be the downfall of them both. Their battle to ruin the other person is an action-packed and tense ride right up until the unforgettable conclusion. No one wins in this exploration of depravity and vengeance. No one but the audience that is.