It's difficult to review as any spoilers will make watching it almost pointless, unless you just want to witness the horror. It starts with a young girl, Lucy, managing to escape from painful captivity in an abandoned building. She is sent to a Catholic orphanage where she is befriended by Anna, who quickly realises that her quiet new friend is haunted by her experience, believing that monsters are attacking her.
The film moves on and the girls are now young women. Lucy believes that she has tracked down her tormentor from the days of her incarceration and dispenses summary justice to the woman and her family. She contacts Anna and at this point, about half way through the film, one doesn't really know what is going to happen next. What does happen is both surprising and shocking, and the second part of the film reveals why Lucy was taken as a child, and this time it is Anna who is to suffer.
As with many horror films religion plays a part, a big part in fact, but not perhaps in the way you may imagine. This is religion at its most fundamental, reminiscent of medieval times, where its proponents seek the ultimate truth and are prepared to inflict great suffering to satisfy their curiosity. And when the truth is extracted? Watch the film, but not if you are of a nervous disposition.
There was an English language remake this year but it seems that it lost a great deal in the adaptation.
Warning - The following trailer is very graphic