I'm sure you've experienced at least one or two of these Camcorder horror movies. The set up is incredibly simple. You take a group of people, equip them with some sort of filming equipment and put them smack in the middle of some terrifying situation. After they die, and they will die, the resulting recording is apparently collected and displayed for your viewing pleasure. This mockumentary style has done much better than anyone expected. To trace the trend you would have to go all the way back to "Cannibal Holocaust" (1980), though if you'd prefer something a little more popular, 1999's "Blair Witch Project" will suffice.
The story in "Paranormal Activity" is as simple as they come. A young couple, Katie (Katie Featherstone) and boyfriend Micah (Micah Sloat) are living the american suburbia dream. They just moved into a two-story house in San Diego and are ready to begin their new life together. Something however is not right. Fearing that some supernatural entity that has been haunting Katie since childhood has moved in with them, they decide to set up a camera in the bedroom to film any weird thing that occurs at night. At first there are just minor manifestations, like moving doors and such. But, as both Katie and Micah start generating negative emotions, like fear and anger, the entity they are led to believe is actually a demon, grows stronger and stronger, eventually becoming capable of actual physical harm. They reach out for help, but it seems nothing in this world can help them.
After a while, you understand how the movie works, you figure out the cue that precedes an event and you somehow try to anticipate the next scare. Surprisingly, even that works in the movie's favor. The more you anticipate, the more you're caught off guard. Sure, it's all very gimmicky, of course. Just like the whole concept of 3D technology is. But it does work and it IS scary. In fact, it's probably one of the scariest movies I have ever seen. Maybe not in the top three, but definitely in my top five. The acting is plausable enough. You know how it works, as long as they can act scared and scream loudly, it's enough. To the director/writer's credit, although the story is nothing new if you've ever watched this kind of stuff on the Discovery Channel, or at the very least seen "Poltergeist", it's all very absorbing. I guess it's because the camcorder tactics add a level of realism that is hard to achieve through regular cinematic means. There are no visual effects. They would just take away from all that realism, anyway. It's kind of hard not to fall in admiration of this kind of filmmaking, especially when it's this effective.
"Paranormal Activity" holds a big record. Besides the $107M box-office on a $15,000 budget (yeah, you read right), it also managed to take down "Saw VI" during its Halloween debut in 2009. Not bad for a movie which was shelved for two years before seeing a theatrical release. A sequel has been released in 2010, but it's nowhere near as solid as this one.