The no-budget ghost story "Paranormal Activity" arrives 10 years after "The Blair Witch Project," and the two horror movies share more than a clever construct and shaky, handheld camerawork.

Like its predecessor, "Paranormal Activity" has been making waves through a viral marketing campaign that has been building positive buzz through early, sold-out college town screenings and Internet chatter. The film`s title has become a nightly fixture among Twitter`s trending topics, despite playing only midnight shows in 33 theaters when it opened last Friday.

This week it expands to 46 markets where it will play throughout the day and evening in more than 170 theaters. And, like "Blair Witch," "Paranormal Activity" is bound to divide audiences who have absorbed the hype.

Best advice: See it early in its run -- and late at night in a packed theater. Half the fun of the movie comes from the communal experience of sharing in something that feels like it hasn`t been market-tested within an inch of its life.

The irony is that Paramount Pictures did initially test the film with the idea of having writer-director Oren Peli re-shoot it with a bigger budget. But the movie, which video-game designer Peli shot two years ago for a reported $15,000, played so well in that one screening that the studio decided go a different route, trimming the length and punching up the ending.

The thinness of the film`s premise is laid bare toward the end, but not enough to erase the horror of those silent, nighttime images seen through Micah`s bedroom camera. "Paranormal Activity" owns a raw, primal potency, proving again that, to the mind, suggestion has as much power as a sledgehammer to the skull.