This film at the beginning is a litle bit confused, but after you watch the hole movie you're adrenalin will pumping so hard....
Esther (The killer) is a 33's year women who looks like a 9 old child. She is orphan, and she always kill all families that adopte her. Because she is skizofrenia patient. The way sehe kill her victim is so sadist. The point is you have to watch to feel that.