If you enjoyed the first three Paranormal Activity movies, you'll enjoy Paranormal Activity 4 too. Despite a little deviation in the third film, this franchise knows what made it work and continues doing that and doing it well.

This, being the review for the fourth movie in a series, is going to be full of spoilers, so read on at your own risk.

In the original, found footage was cobbled together to try to make sense of what happened with Katie and Micah, two people who recently moved into a new house. At first it appears the house may just be haunted, but as the film progresses we learn that this isn't a ghost but a demon and it is a demon that is coming directly for Katie. The footage is captured by Micah, who initially becomes obsessed with capturing the ghost footage and puts up a couple of cameras in the house to that end. The film ends with Micah dead and Katie, having become possessed by the demon, running off into the night.

The second film was well done and wrapped around the first film as both a prequel and a sequel. Kristi, Katie's sister, has recently had a child. She and her husband Dan's house is broken into and shortly thereafter strange things start happening. Katie visits and the sisters talk about a demon who tormented them as children. Ali, Dan's daughter from a previous marriage, starts investigating the haunting, recording everything, and finds out that people can make deals with demons by promising their first born male. Dan and Kristi's new son Hunter is the first born male in the Katie/Kristi bloodline since the 1930s. The haunting escalates to violence and Dan performs a ritual to transfer the demon's obsession to someone else... Katie. [Insert the original film here.] Katie, now possessed, returns to Dan and Kristi's home, kills them and kidnaps Hunter.

In the third film, we start before the break-in that started the second film. Katie brings a box of video tapes over to Kristi. The tapes are stolen during the break-in. The rest of the movie comes from those tapes, made in 1988, when the girls were little and the demon first appears. We also get a name for the demon, Toby. Oh, and a coven of witches. Anyway, most of the recordings here are done by Dennis, boyfriend of the girls' mother.

Which brings us to four... and back to the present, 2011. We meet an entirely new family: Holly and Doug, and their kids Alex and Wyatt. Alex's boyfriend Ben starts off the recordings as the two of them find Robbie, a new neighbor, hiding in their treehouse. The next day, Robbie's mother suddenly falls ill and is rushed to the hospital. Holly and Doug decide to be good people and take care of the boy until his mother can come home. Robbie is weird and has an imaginary friend... named Toby.

Paranormal Activity 4 is full of the same stuff that worked in the other films and continues to work here. Cameras set up around the house, this time employing more webcams on laptops than anything else, capture moving doors and floating shadows. There is a neat trick employed here with an Xbox Kinect and night vision allowing us to see things invisible to the naked eye.

There are two downsides to Paranormal Activity 4. The first is the over use of blocking the camera. Constantly things approach the camera to obscure the view and rarely clear away to reveal... nothing. Doing the blocked-shot/reveal is good, when used in moderation. Doing the blocked-shot/no-reveal is also good, when used in moderation. They threw moderation out the window. The second downside is knowing that Paranormal Activity 5 is coming - so, no resolutions here.

Still, a decent film. Great even, if you are invested in the series.

The Blu-ray has an extended, unrated cut of the film, as well as 30 minutes of extra footage. Nothing that makes this a must buy, unless the movie is all you really want.