Found-footage horrors have enjoyed a resurgence in popularity, thanks in part to the likes of Paranormal Activity, The Last Exorcism and various other copycats that have sprung up in the wake. As is often the case with horror, and indeed found-footage horror, the first film is often the best because it's a new idea or a new take on a worn idea. So it goes with Unfriended, the first film we can think of that's set entirely in a computer screen.

Told through one computer screen, that of Blaire (Shelley Hennig), Unfriended is a truly inventive horror movie. A group of high school students / horror archetypes meet via Skype to discuss an upcoming event in their school calendar. Unaware to all except one, it's also the anniversary of a fellow student's suicide. Laura Barns, who was a friend of Blaire - the girl's computer screen we're seeing - committed suicide after a video of her in a drunken state was uploaded to YouTube and shared across social media.

An innocuous Skype group conversation begins with an unidentified interloper, whom the group believe to be just a random troll. Parallel to this, Blaire receives a Facebook message from Laura's account. Slowly but surely, the group are made aware that a reckoning is due for Laura's suicide by a sinister presence. Skype, Facebook, Liveleak, iMessage are all used as settings for the drama and horror that unfurls and, in the space of ten minutes, you almost forget that it's not your screen.

It's a fascinating concept, to say the least. We're so used to looking at a computer screen and almost removing ourselves from it that when you watch Unfriended, you really do feel like you're a part of the story. The performances are, by and large, very well constructed and the script feels authentic and real. The fact they're teenagers adds to the story. Of course they're going to be histrionic if a compromising photo is posted on Facebook. Anyone would, sure, but these teenagers take it as their life. As the story progresses, the supernatural element takes hold and, as you'd expect, the characters are picked off in increasingly gruesome circumstances.

Director Levan Gabriadze knows how to build a sense of dread and malevolence. There's little flourishes of brilliance here and there that adds to it; the unsettling feeling when you can't Unfriend someone on Facebook, the knowledge that someone knows exactly what you're watching on YouTube.

Despite all these positives, however, there are some setbacks. As previously mentioned, the characters are somewhat one-dimensional archetypes. You have the virginal beauty, the jock, the smart one, the promiscuous one and the well-meaning boyfriend. Likewise, the knowledge that they're all going to meet a grisly end is clear as soon as the action kicks off. The narrative does require a working knowledge of social media and the Internet, but Nelson Greaves' script is good enough that you can understand the basics of what's happening without too much thought.

In all, Unfriended is a surprisingly inventive take on found footage. The real horror in Unfriended isn't necessarily the demon that stalks these teenagers - it's the permanence of the Internet.