If you like these type of movies (found footage) - you won't be disappointed at all
This one is pretty good. It picks up from where Paranormal Activity 2 leaves off where the possessed Katie (Katie Featherston) disappeared with her infant nephew, Hunter They replay that scene from 2006 at the beginning so if you didn't see anything after the first flick, you'll immediately get a quick scare at the beginning to set the tone. The the film moves forward five years to introduce a family of four living in a Nevada suburb: You have the basic working dad (Stephen Dunham), frenzied mom (Alexondra Lee), young son Wyatt (Aiden Lovekamp), the typical "Tween" daughter Alex (Kathryn Newton) and her boyfriend (Matt Shively), who is a bit of a computer whiz. So right there you've got a guy who can rig every computer in the house to film the activity in the house (the most important element to the "found footage" genre) . And he plants a few cameras in walls as well. But why?.
A kind of strange neighbor boy named Robbie (Brady Allen) with an imaginary friend, comes to stay with them for a few days because something happened to his Mom. Some weird things begin to happen around the house. When Katie suddenly appears, it implies that Robbie may be Hunter, though it seems she has some dark designs on young Wyatt.
It follows the basic format of the first 2 and the suspense builds and by the ending it really pays off (we won't ruin anything) and also sets you up for Part 5. They've found even more ways to be creative with household objects and they've incorporated the use of the XBOX Kinect and the beams of light it shoots out, that you can only see with infra-red.