I see almost all movies my public library buys and this is one of them. Plus I have become a fan of sorts of Jennifer Lawrence, the camera really loves her face, she is a natural to become a real "movie star." While I certainly would not put this movie in my list of top movies, it is rather well made and the story held my attention.
The rest of my comments contain SPOILERS so don't read further if you haven't seen the movie.
The first 4 1/2 minutes take us right into the center of the mystery, we see a daughter of maybe 13 or 14 kill her mother in the home then go into the bedroom and kill her father, then she runs away through the woods. Later we are told she was presumed to have drowned.
It is now 4 years later, Jennifer Lawrence is teenager Elissa, she and her mother, Elisabeth Shue as Sarah , are moving from Chicago to this area and are renting the house just a short distance away, through a small stand of trees. They are told the house is vacant but Sarah sees a light on late one night. It turns out the deceased family's son, Max Thieriot as Ryan, lives there apparently alone. But we find out he isn't alone, he is keeping his sister Carrie Ann hidden in a basement room, apparently taking care of her.
But nothing is as it seems to be, as Elissa finds Ryan smart, gentle and interesting, we find out he is actually deranged. When his sister had actually died in a childhood swing accident, in flashbacks we see that his parents blamed him and tried to raise him as their daughter. It was actually Ryan dressed like a girl that had killed his parents during the night, and in present time he kidnaps teenage girls, imprisons them in his hidden basement room, puts blue contacts on them, and calls them Carrie Ann, his deceased sister. When he accidentally kills one he disposes of the body then gets another one. It seems Elissa might be next.
In the final scenes Elissa breaks free of her restraints, while Sarah comes looking for her, and together they get the upper hand, just barely. As the movie ends Ryan is in a mental ward.