A thriller just for the sake of it. You are going to like it, if you don't dig deeper into the logic. Yes, there are plenty of questions you might ask throughout the film, it may affect the viewing experience. Korean films are awesome in making thrillers, but this is not the perfect one.

This movie could have been good, but it's ruined for me by characters making too many stupid and unrealistic choices when it comes to their actions. Warning, spoilers ahead:

• You're in a taxi with a friend, and all three of you spot a guy seemingly beating on a woman in the street. Your friend quite literally thinks it looks like he's going to KILL the woman at this rate, so she asks you if maybe you shouldn't call the cops? Your response? Naw, you say. No good will come from getting involved...Are you kidding me?

• Your sister is babysitting your kids while you are at work at your radio station as a radio host. Someone calls you, and tells you they are holding your family hostage, and that if you don't play the songs they tell you to, they will hurt and/or kill your family. They also mention a playlist they have sent you with the songs in question, but you don't yet know what they are talking about, since the playlist in question was inside a package you unwittingly threw in the trash earlier, thinking it was from some stalker fan. You're not sure if it's a prank or for real yet (I would take it seriously and not risk it), so you then try to call your sister, but you are unable to reach her. What do you do at this point? At this stage, the normal thing to do would of course be to call the cops and tell them the facts: that someone called you claiming they are holding your family hostage, and are threatening to kill them, and that you tried calling your sister, who is currently babysitting your children, but you couldn't reach her. The cops will then most likely consider it a possible genuine threat, and send a response team, and, knowing the situation, and that your sister and kids are the only ones supposed to be in your apartment, will be on their guard and go in armed, and they will know what to expect, and what to react to if something is wrong. But what does or protagonist do? She instead calls the cops and simply tells them she is unable to reach her sister at her apartment, and if they can send someone over to check on her...No mention of the threatening phone call, no mention of who is and isn't supposed to be in her apartment...Like come ON...The cops are nice enough to send two officers over (they could definitely refuse with so little info. People missing phone calls isn't exactly unusual), but being relaxed and not knowing the situation, they are fooled by the killer opening the door, since he simply tells them he's the protagonist's brother, and when the officers come in to make a routine check, they of course turn their backs to him, unarmed, because they're not expecting anything, and aren't on their guard. So the killer catches them off guard and kills them from behind.

One of many Korean serial killer movies that came out in the wake of the excellent THE CHASER. This one's not the greatest, but it still manages to hold the viewer's attention for the whole of the running time, so that counts for a lot. I struggled with the lead character in this one - I found her so cold and unyielding that it was impossible to empathise with her plight - but an early role for the excellent Ma Dong-seok is worth tuning in for, and the Koreans' enjoyment of cat and mouse games means that the suspense holds even when dragged out to the nth degree.