Box office phenomenon

Paranormal Activity is a fabulously unsettling horror film - and fabulously successful at the box office - because it seems so real.

Powered by automated translation

I am in a darkened cinema at midday. The girl next to me can barely watch the scene unfolding before us. She starts hyperventilating. She covers her face with her fingers, but it's clear she's looking through them. A dark shadow passes across the screen and immediately I hear a different noise from my neighbour. She is quite audibly weeping. Welcome to the horrifying world of Paranormal Activity.

Oren Peli's debut film is so fabulously unsettling because it is so real. It plays much like a sequel to The Blair Witch Project. A likeable young couple, Micah and Katie, are haunted as they sleep by something mysterious but (at first) not necessarily threatening. So they record the things going bump in the night on their video camera in order to make some sense of them. How on earth they are able to sleep at all in their clearly haunted new home is something of a mystery, but nevertheless they set up the camera on a tripod before they go to bed and leave the door open to see what happens. The film is brilliant in its repetition of the footage of their darkened room. Night after night, something genuinely chilling happened, but finding out what or who is responsible is just as intriguing and appalling for the audience as it is for this troubled couple.

Yet this is no bloodthirsty, big-budget box office bid. The film is already three years old, and was made in a week for $15,000 (Dh55,100) at Peli's house. The camera work is shaky because there were virtually no cameramen: Katie Featherston and Micah Sloat (the film uses the actors' real names) hold the camera as they act their parts. Paranormal Activity was one of those films destined for the horror festival circuit until a DVD landed at the film company DreamWorks. A fan of the film at the company pestered executives to watch it until Steven Spielberg finally took it home one night.

Legend has it that he was so haunted by the film that he brought it back to work in a rubbish bag because he was so afraid of the contents. Whether that's true or not, Spielberg was certainly impressed. He began a big-budget remake, still with Peli as the director. But a test screening of the original just before filming was due to start revealed something incredible: it terrified audiences because it was so real, low-budget and plausible, rather than in spite of it. So Spielberg suggested a new ending, and that money-can't-buy word of mouth buzz began.

The blogosphere lit up, and after a viral campaign that asked people to request the film in their hometown, Paranormal Activity is the most profitable independent film ever made, already earning more than $100 million at the box office. Reactions have been mixed. Certainly younger audiences who have grown up on the blood-splattered, in-your-face horror of the Saw series won't find much action to grab hold of here. It is a more thoughtful, psychological film in which a door moving backwards and forwards or a light switching on and off by itself are signals for terrifying feelings of unease. It is why audiences in their late 20s or thirtysomething couples will probably not sleep after watching it - and why they may brood at the subtext of the difficulty in ever knowing another person or getting over the ghosts of their unshared past.

Inevitably (and perhaps a little annoyingly), plans have been made for Paranormal Activity 2. It's difficult to see how this will work unless the studio sets a miserly budget for an up-and-coming director and asks him or her to come up with something that fits. Even then, it will be going over old ground. Paranormal Activity's brilliance is that it certainly nods to other films (in a neat reference to Psycho, Micah checks the shower for the demon) but fashions something completely new from an effortlessly simple idea. As Blair Witch 2 proved, sequels of this sort rarely work.

Much more interesting is what Peli is working on next: Area 51, a documentary-style thriller based around the famous Air Force base in Nevada that again uses a "found-footage" video technique and unknown actors. So he's on similar ground, except this time it cost $5m rather than $15,000.