I have seen this film twice and after the second viewing, I came to the conclusion that although flawed, the film does contain several unsettling scenes. Overall, I think it is a study of the mental disintegration of the central character, David. How this is achieved is partly through the inclusion of some of the most gruesomely imagined monsters ever to appear on screen. The fact that we only see them briefly and often in half-light is a bonus. By the end of the film, I understood that all four characters are going through a groundhog day experience, from which there is no escape. This is what makes the film very disturbing, leaving a rather bitter aftertaste. We need more British horror movies like this, which show an imagination that no American director could hope to achieve without sacrificing credibility. I would also include "Salvage", "The Disappeared", "13 Hours" and "Outpost".
