The storyline in I Saw the Devil is simple enough: a serial killer abducts and brutally murders the fiancée of an elite National Intelligence Service operative, and the young man devotes himself to tracking down the killer and eliminating him; however, instead of focusing on the protagonist, Soo-hyun, finding clues, and pursuing Kyung-chul, the killer, director Kim Ji-woon and writer Park Hoon-jung weave a tale of how thin the line is between humanity and monstrosity. Soo-hyun appears to be a loving fiancé and moral agent before he loses Joo-yun, and, initially, it seems as if he will merely be a vigilante hero who makes sure that a horrific criminal receives brutal justice. As the story progresses, though, Soo-hyun shows a remarkable ability to hurt others in the name of righteousness, and his sadistic behaviour escalates rapidly. By the final scenes of the film, I’m not sure there is any redemption left for our protagonist, but the ending leaves some room for interpretation.

Obviously, I Saw the Devil abounds with violence and gore, but why exactly does it cause chills to run down my spine when watching the movie alone in a dark room? First, all of the villains in the story are human beings with no supernatural abilities or influences. Admittedly, they’re horrible, possibly mentally warped people who do atrocious things, but there is no ‘other’ to blame for the story’s events. Second, Soo-hyun’s descent reveals the fragility of what we generally consider humanity. Whether our protagonist is really a closeted sociopath the entire time or loses his grip on kindness when his beloved is brutally killed is up to the viewer to decide. The transformation shocks and frightens me, and while I don’t sympathize with Kyung-chul, the cannibal, or any of the criminals that cross Soo-hyun’s path, I mourn the loss of the kind, apparently gentle young man who won Joo-yun’s heart and loves her father and sister like his own family. Lastly, and perhaps most horrifyingly to me as a female viewer, the women we see Kyung-chul abduct do everything we are taught to avoid becoming victims. (Okay, the second girl does get in a car with a stranger, but she was also at a deserted bus stop after dark.) Joo-yun stays on the phone with Soo-hyun, cracks her car window to avoid being grabbed by the stranger, and keeps her doors locked, but she still isn’t safe from her killer’s murderous rage/intent. My tension rises just remembering that scene, since it reinforces a fear many women carry in the back of their minds that no matter what we do, we can still be overpowered, hurt, and discarded by those who want to do us harm.

The sheer quantity of gore in I Saw the Devil will put it outside of many viewers’ comfort zones, but I do think it’s a chilling Halloween watch. Just be prepared to lock your doors, give your neighbors the side eye, and avoid dark, deserted roads for a while afterwards, because you won’t know if you can trust anyone to be who they seem once the credits roll.