Since there's lot of reviews but not all of it understanding. So here why, let see the first scene.

This movie the character is purely psychopath who just killing person right. The character shows he have kind of hunting the victim for fun, laughing and like mouse and cat.

I found a comment say ' why didn't the mother end the everything in Police Station? '. Yeah, that's right they can end everything on the spot. But not so fast 'he' know what is happening and try to control the situation. Even how much smart her mother is, she can't exposes that easily. Cause why? she doesn't want her daughter in danger. Her daughter is her priority.

'It doesn't make sense you can't realize there someone on your back'. Actually it possible you didn't realize, I didn't just talk. I can stand behind someone without they realize, breathing slowly and didn't make a big move. But you need to remember she deaf her world is quiet. It can possible when you to focus on phone you can't even realize your friend beside you.

'Why he run to the deaf woman house without calling a police first? '. In that situation you usually have two choices but the reflex usually kick first. He want find that bu*ted first, cause why? He think about her sister safety first that's why be became stupid to safe her with eagerly. He scared if he gonna lose her forever.

About the police, I just to frustrating to see them. So bad.

And at the street you can see Kyeong Mi eagerly need help, but no one is helping right. First you need to see the situation, all of the people there didn't understand what is happening. They make they own assumption by thought that girl might be crazy or something. Since you can just only see she holding knife and her shirt have a blood stain. They feel pity to her, that's why the 3 soldiers help Do Shik, without even realize they help the psychopath. Do Shik know how to act innocently in front of people, how can you know he psychopath when he can act that perfectly fine.

At the end you can see Kyeong Mi decided to act reverse, instead stab him she stab herself. Nothing can defeated him if you still act like naive to him. Cause he can flip that image easily.

I ready to talk if you want more explanation