This film is an efficient thriller from Spain. It deals with the popular urban legend of "snuff" films (films which depict a real-life murder committed purely for the sake of the film).
The plot involves a young film student Angela (Ana Terrant) who is doing a thesis on cinematic violence. To research her thesis she seeks out the most extreme violence films she can find and accidentally stumbles upon a snuff film depicting the torture and murder of a fellow student from her university. She soon starts investigating the film.
The film is well-made and well-acted with several effective scares and twists. It's main message is that the people who watch violent films are in some way accomplices to the violent acts that they watch. This is an old point that has been made several times before. It also deals with the attraction of the forbidden. For example, in the opening scene, Angela goes to see a dead body on a railway track, partly because she has been told not to. Just when she, and the audience, are about to see the body she is stopped. In another scene, Angela is looking away from the snuff film but takes a quick look when she is told not to.