The scariest thing about "Paranormal Activity" is how it plays on your fear of being afraid. The funniest -- and naughtiest -- thing about it is the poster -- the shot of the occupied bed in the dark room above the title "Paranormal Activity." But it turns out that what goes on in and around that bed is indeed what interests the camera. It also suggests to me something Errol Morris raised in his nonfiction film about Abu Ghraib, "Standard Operating Procedure": Would all this be happening if cameras hadn't been present to record it?
Hold that thought for a moment, and let's look at the premise: Katie (Katie Featherstone) has recently shacked up with her boyfriend of three years Micah (Micah Sloat) in a newish San Diego tract home. He's just bought a new video camera because, well, there are a few things Katie neglected to tell him about herself. Like, for instance, how something -- a demon, probably -- has been following her since she was eight years old. OK, so here's the source of the conflict in their relationship now: He thinks that's kinda neat and wants to get it on video, so he can deal with it and get rid of it and rescue his gal. He sees himself as the Man of the House, the Protector, after all. She doesn't want to mess with it, and has contacted a psychic (by phone) who tells them that whatever's following Katie is not human, that demons are not his métier (he's a ghost guy), and that they should get ahold of this other fellow (a demonologist) who may be able to help them.