I think the main reason this movie has so many low scores is the fact the horror elements are few and far between, and is really more of a thriller with some supernatural elements thrown in, which really add nothing to the story, and just feel like they were thrown in to up the fear factor. The much over used "Inspired by actual events." tag is obviously referring to only a tiny element of the storyline, the rest has been filled in by the writers and directors to make it more exciting.
The basic storyline, a woman who's husband has disappeared a few years before, leaving her and her young son behind, now has a new fiancée. Soon after their engagement, the man's mother's house keeper quits, and he has to travel up to look after her as she has some undisclosed illness, but is most likely dementia. As it is the start of the summer holidays, the young mother and son travel with him to the country. Of course the old woman is creepy and lives in a creepy old house in the middle of nowhere. Oh, and the power keeps going out. That is really the set up for the rest of the story. A few spooky things happen, The fiancée has to keep leaving her and her son alone overnight to go for work meeting, or visit a care home to find a spot for his mother.
The ending is a bit of a damp squib and feels like a cop out, but if your not expecting a rollercoaster horror ride, you might enjoy.