MOVIE REVIEW: "Paranormal Activity 4" 

SPOILER ALERT! There will be a "Paranormal Activity 5" in... oh, I'm gonna guess exactly one year from now. The first three films in the "Paranormal Activity" franchise have banked a little north of a half-billion dollars worldwide, and in comparison with how much they cost to make, the gross is almost pure, uncut gravy. Oren Peli's original "PA," you may recall, became a surprise hit in 2009 a la "The Blair Witch Project," thanks to a lean, ingenious found-footage premise that delivered jolts from screwing with our tightly wound psyches rather than assaulting our eyes with torture and gore. The sequels followed the "If it ain't broke" rule, finding inventive ways of sticking to the formula while telling the evolving story.

Which brings us to the disappointingly utilitarian "Paranormal Activity 4," a film strictly for those who've seen 1, 2, and 3. (But if you haven't, then scram now, or learn some things the rest of us already know.) "PA4" opens with a brief refresher of scenes from the end of "PA2," with common-thread Katie (Katie Featherston) claiming her young nephew Hunter and padding off into the night in bare feet and blood-covered pajamas. Flash-forward five years to the fall of 2011, where we meet 15-year-old Alex (Kathryn Newton), who lives in suburban Henderson, Nevada, with her squabbling parents and little brother Wyatt (Aiden Lovekamp). Much of the footage in "PA4" is courtesy of the tech-friendly Alex, constantly connected to either her phone or her laptop.

Alex begins to notice odd things happening after Wyatt befriends the boy across the street, a pint-sized weirdo named Robbie (Brady Allen) who bunks with Alex and her family after his single mother (wink!) is carted off in an ambulance. It's Ben (Matt Shively), Alex's thick-necked doofus of a maybe-boyfriend, who sets up the stationary surveillance we now rely upon to provide the frights in the "PA" movies. And you can pretty much envision what happens: balls mysteriously bouncing down stairs, chairs suddenly moving, loud noises, kids talking to a seemingly empty room. Then those words appear on the screen: "Night No. 1, November 6, 2011." It still sends a tiny chill up the spine as the film begins counting down to... something.

Oh, I don't know why I'm being so coy; "PA4" is the same as it ever was. The frights start escalating in frequency and violence, leading to an expected and slightly silly but nonetheless manic denouement of flying bodies, slamming doors, and terrifying faces as the film sets up the next chapter. Returning after of the success of "PA3," co-directors Henry Joost and Ariel Schulman (they also made the polarizing documentary "Catfish") maintain the status quo, but they — presumably by way of screenwriter Christopher Landon — find a way to get much clever visual mileage out of the family's Xbox 360, using its Kinect motion-sensor technology as a way to suss out demonic presences like Toby, who you may remember from "PA3" as young Katie's not-so-imaginary friend.

As central characters go, Joost and Schulman could have done much worse; Newton does an admirable job of anchoring "PA4" as the engaging, vulnerable Alex, skillfully offering up the natural teenage mix of curiosity and trepidation at an unfamiliar situation. Unlike the rest of her amateurish castmates, Newton almost prevents us from trying to poke fat holes in the film's execution. For instance, why is no one ever allowed to finish an explanation? And how can you still hold onto your laptop when something is scaring the stuffing out of you? Trafficking in the economical notion that what you can't see is far more frightening than what you can see, "PA4" is still able to deliver some spooky moments, and even a few funny ones, too.

I've often wondered whether Peli envisioned this entire arc when he first created "PA1" or if he and his team are now kind of assembling the "PA" mythology on the fly. (I'm leaning toward the latter.) Less so than the possibly superfluous "PA3" — time will tell on that front — "PA4" really feels like a stepping stone, a way to make a quick buck before what will hopefully be positioned as the big finale. (Until a $50 million opening weekend, of course.) Don't get me wrong; I'm still totally interested in seeing what happens with Katie, Hunter, and the ever-intriguing Toby. But "PA4" may be about as close as you can get to actually drawing blood from that dead horse.