Interesting [spoilers]

This movie was difficult to understand because of the terrible captioning. But here's what I have put together: So yeun asked her little group of friends to help her play a prank on her sister Hyo Jin. Somehow it involved luring her to the end of the pier. The confusion comes with the bracelet. Who did the bracelet belong to? Who grabbed it off the other's arm and left a scar? It seems that the girl pulled to safety was both wearing the bracelet *and* had a scar. I think the presence of the bracelet made the mom think she had pulled So yeun to safety, when it was actually Hyo Jin.

Hyo Jin wakes up and is told she's So Yeun. But she behaves nicer, more like Hyo Jin. The boyfriend, who wanted to break up with So Yeun anyway, starts to like her now and decides he does want to marry this new So Yeun. Meanwhile the friends who helped with the mysterious prank start dying, and everyone thinks it's either So Yeun or the ghost of Hyo Jin. At the end, when the living twin faces the ghost, it seems to be Hyo Jin facing the ghost of So Yeun, who asks her how she likes being hated by everyone. And finally at the edge of the pier, the mom must choose again which daughter to rescue. The good twin, Hyo jin, resigns herself to death and tells her mother to rescue So Yeun. The mom does, jumping in with her and embracing her as they sink. And happily the boyfriend arrives in time to rescue Hyo jin, and we can assume they live happy ever after.

Because the ghost twin's face was in the back of the living twin's head, I had the impression that both girls' spirits were living in Hyo Jin's body. Which to me explained why the ghost's body was also grown up. Also, things that should have been with the killer twin would show up among Hyo Jin's things, as if they were sharing a body?

I can't help but feel if this movie were well captioned, I would have understand it better.

P.S. That thing with the black sesame seeds in the girl's skin is a nasty image that's hard to shake! Blech!