Sequels are practically inevitable in the film business these days; if a movie makes a profit, the smart money says there’s going to be a follow-up, and it’s all but etched in stone that a horror movie that does well is bound to become a franchise. For scary pictures, the third movie is where things get complicated -- will the second sequel be strong enough to insure that it will go on spawning future chapters that will clutter cable TV and video-rental outlets for many years to come, or after three strikes, will the beasts be driven back to the land of unprofitability? Since Paranormal Activity
and its sequel Paranormal Activity 2
both managed to gross...