Dean Hendler / Paramount Pictures

A shock to the system is an event. Someone tiptoes up behind you and goes boo! A car zips out of a side street into your lane. A door slowly blows closed. That last one, in the original Paranormal Activity, made movie audiences jump in tandem, as if ordered to by a gym teacher. Ah, the pleasures of horror-movie subtlety: when the conventions of the genre are stripped to the bone and the scariest part is not the monster but the waiting. In so many ways, Oren Peli’s film proved that less is more. Shot in a week in 2007 for $15,000 and finally released in 2009, it earned $193.4 million at theaters around the world. PA and its two sequels have totted up a $576.6 million global gross on a production investment of about $8 million, or a $72 return on every dollar spent shooting.

But when you expect the shock — hear the tiptoeing, spot the car, see the same spooky door in another film — that’s merely a habit. Attending a Paranormal movie is now just that: a rite of fall, with predictable autumnal shivers, like a Halloween jaunt in, say, Alaska. Not missing a trick, or a treat, the entertainment-industrial complex has extended a single fright night into an entire season, in theme parks (Universal Florida’s Halloween Horror Nights, which stretch over six weeks beginning Sept. 21, now in its 22nd year), at kitsch museums (Madame Tussaud’s Chamber of Horrors) and in Hollywood’s fall schedule of pre-Halloween horror films. This year The Possession began the ghoul parade in late summer, Aug.31, and it has continued with a new haunted-house movie nearly every week.

(READ: Corliss on the Paranormal phenomenon)

As the series that challenged Saw, the previous pre-Halloween king, and quickly beheaded it, the PA franchise has stopped innovating and turned into a familiar theme-park-like attraction: the same reliable, recyclable experience, the same methods employed with the minutest variations. That’s certainly the case with Paranormal Activity 4, which will lure about 5 million people to theaters this weekend. The movie is an October surprise without the surprise. You go not to be scared but to remember the thrills you felt watching the first film. Instead of a journey into fear, PA4 is a nostalgia trip — déjà boo! all over again.

In the first movie, set in Carlsbad, Calif., in 2006, Katie Featherston and Micah Stoat (the actors used their real names) moved into a house that gave hints of being in a really bad mood. The door moved; shadows crept across walls; an unseen figure slipped under the bedcovers. We saw this because Micah had set up a video-recording device in the bedroom; a timer spun or froze to capture the inexplicable evidence. (SPOILER ALERTS coming on plots of the first three films:) By the end, Micah was dead and Katie demonized. PA2 operated on parallel tracks with the first film, showing Katie’s sister Kristi (Sprague Grayden) and her son Hunter; Katie kills Kristi and abducts Hunter. The third film flashed back to 1986, when Katie and Kristi were kids and the root of the trouble — a coven of demons — was revealed.

So far, so cool. The second and third episodes, though lacking the innovations of the original, built on its found-footage ingenuity and point-of-view rigor. PA3 was directed by Henry Joost and Ariel Schulman, who had invested their “documentary” Catfish with such rich characterization that TIME named one of its subjects as a Best Performer of 2010. Given the reins again for PA4 — and again directing a script by Christopher Landon (who wrote the second and third episodes — Joost and Schulman were expected to lend body and (lost) soul to the central mythology, for this is the first film to move the larger story forward chronologically from 2006.

(READ: Mary Pols’ review of Catfish)

It’s now 2011 in Henderson, Nev., and we’re in the home of a normal-for-now family: Mom and Dad (Alexondra Lee and Stephen Dunham), their 15-year-old daughter Alex (Kathryn Newton) and 6-year-old son Wyatt (Aiden Lovekamp). When the woman who moved into the house across the street is taken to the hospital with an unknown complaint, the family takes her moody son Robbie (Brady Allen) in for a few days. Stuff happens, and to record the spookiness Alex’s boyfriend Ben (Matt Shively) hooks up more surveillance equipment — Mac laptops, XBox Kinect, Skype — than Claire Danes sneaked into Damian Lewis’s home in the first season of Homeland. Need I say more?

O.K., thank you, I will. (Hardly any SPOILER ALERTS here. Most of this is revealed in the trailers.) A basketball slowly bounces down the steps to the living room. Mom’s kitchen knife flies out of sight when she isn’t looking. (It’ll be back.) Robbie’s invisible friend becomes, in night vision, semivisible. On Wyatt’s bedroom wall, the invisible friend scrawls his name: Hunter. Robbie warns Ben, “He doesn’t like you”; and when Ben asks, “Who doesn’t like me?” the child replies, “You’ll find out.” Wyatt, who was adopted, says, “My family needs me back.” Plus a levitation, a neck snap, a creepy bathtub scene, some mischief in a garage and the return of the Katie coven.