Ten years after "The Blair Witch Project" flew onto the screen comes "Paranormal Activity," another movie based on fictitious "found" video.

This movie wisely has been distributed in ever-widening markets so that word of mouth precedes it. And for good reason: It's not so much a horror movie as it is a study of the supernatural and a couple's relationship. It's creepy. There are no severed limbs or gorefest scenes - just the troubling presence of something that seems to grow ever more malevolent.

It's more about atmosphere than it is about shock.

Supposedly composed of "lost" video found in the couple's home, the show begins with a thank you to the families of Katie Featherston and Micah Sloat, the actors' real names.

Katie and Micah are living together in San Diego. They're "engaged to be engaged." He's a day trader and she's a student.

She has had some kind of presence haunting her from time to time since childhood. Now it has manifested itself in more apparent ways. Micah is fascinated by this turn of events. He buys a video camera and begins to either carry it around or set it near their bed where it can film whatever transpires at night - usually in the wee hours of the morning.

The next day, Micah watches the footage on his computer screen. He and Katie recoil when they see their bedroom door open and shut by itself. The thumps and noises continue to intensify over the next few nights - so much so that Katie consults a psychic. He tells them some sort of demon is terrorizing Katie and that it will follow her wherever she goes.

And then events begin to escalate. Micah wants to buy a Ouija board, but Katie doesn't want him to. One of the most bizarre and chilling moments occurs when she gets up in the middle of the night and simply stands by the bed, staring at Micah. Her strange behavior is part of the film's overall tension.

Is the storytelling format a gimmick? Well, yes, but it's a clever one. It's not always what you see revealed on the video camera but what the director leads you to imagine that's truly terrifying.

"Paranormal Activity" won't necessarily scare you out of your seat. But it's likely to creep you out.