This slick little psychological UK thriller revolves around a bullied school teacher, who has to face his demons after his school is taken over by faceless hooded thugs who set about systematically tormenting and killing off staff and students alike.
Made on a shoe-string budget (around £150,000), and with next to no gore or on-screen killing, F really was going to go one of two ways but thankfully it succeeds in dishing out decent chills and genuinely creepy atmosphere, making this a much more cerebral horror, compared to your run-of-the-mill blood and guts fest.
The hooded assailants work brilliantly, as we are never quite sure who they are, why they are there, or even whether they are human or something other-worldly. As the viewer, you are never really presented with any character you can sympathise with or root for, they are all pretty dis-likeable, and this might not sit well with some. Personally, I didn't mind as the lack of character connection means you can sit back and enjoy when someone is picked off by the thugs.
What really seems to be rubbing people up the wrong way is the film's ending. Without giving too much away, those who like a film to be wrapped up neatly in a bow, with no loose ends will be seriously annoyed. Personally, I found the ending quite refreshing - it doesn't allow us as the audience to sit back and relax, it send us away with a knot in the stomach, knowing that, just sometimes, things don't always finish with a Hollywood ending.