A man appears in the office of the father (which is a psychologist) and tells them what haunt him and his family and that led to his young children being killed off. Then he died/commited suicide in their home.
After this moment, the young child starts seeing stuff in the dark and nobody believe her, it was spooky and young child really got her part. Then step by step the older child starts to believe and tries to understand what happened to the previous family.
Then it's confrontation time and I will have a minimum spoiler, so beware, but it was a bit idiotic the ending. For a monster who has lived forever preying on humankind it sure is killed easily, and it got shot before a lot of times and nothing killed it but fire? OK, but we see him putting out candles so... I don't know it felt weak.
Spoilers end.
What I enjoy was the family stuff, how they grew as a family trying to work things out. The problem is the all monster stuff I couldn't get into.. why didn't the monster kill the two children when it could? Oh well..