It needed to explore other aspects of a relationship. I was more interested in the daughter story and the killer thinking he was rank A than Bok-Soon. It was hard to understand why she was doing what she was doing and how she ended up there.
The action scenes are the reason I stayed especially the last one which shows all the scenarios thinking it was real but wasn't. The ending ruined it as I wanted an honest conversation between them so there are shields but I got deflated.
It could've done so much better as I wanted more character and their development in the movie