When this dirt-cheap (that’d be $15,000) frightfest opened in late September for midnight showings in a dozen college towns, cynics laughed at its viral marketing campaign. Paramount Pictures asked interested parties to log on to a website and vote to get the flick into their towns. No one’s laughing now. After a million-plus requests, Paranormal Activity is everywhere and raking it in ($34 million at last count). On a cost-profit basis, PA may be the year’s most profitable.

What’s all the excitement about? Oren Peli’s movie from nowhere owes much to The Blair Witch Project, and, OK, suffers by comparison. But make no mistake, it will fry your nerves and creep you out big time without spending a dime on obvious special effects. The plot needs three sentences. Katie (Katie Featherston) and boyfriend Micah (Micah Sloat) are freaked out by noises in their San Diego home. To catch what’s out there, he sets up a night-vision video camera while they sleep. We watch the found footage.

That’s it. Over a period of about three weeks in the film, the tension builds and builds and builds until the dread ties your stomach in knots. No need to say more. If ghost stories have your number, this one will get you good, proving you don’t need stars and computer mash-ups to make audiences shriek at things that go bump in the night.