PHOTO © SONY PICTURES

In every long-running franchise, there is a chapter that clearly and unambiguously demonstrates that the concept no longer works.

“Insidious” just got there.

The long-running series about astral projection and spooky demons produced four fairly well-received installments between 2011 and 2018. At the time, the haunted-house aesthetics and relatively gore-free plots were refreshing after years of bloody romps such as the “Saw” franchise.

Over a decade later, however, old-school creepers are ubiquitous. There’s also been a five-year break since the last “Insidious,” and a 10- year break since the last non-prequel (don’t ask), “Insidious: Chapter 2.” So “The Red Door” is not merely overdue, it’s relying on plot details that may well be forgotten.

The short version: As a child, Dalton (Ty Simpkins) accidentally learned he could project his spirit while unconscious, roaming around and eventually getting tangled up with some sinister creatures in a shadow plane dubbed The Further. His father, Josh (Patrick Wilson), rescued him, but later got possessed and nearly killed the family while under the control of a restless spirit.

In “The Red Door,” Dalton is off to college, where an art instructor inadvertently sends him back into The Further, much to the dismay of his dormmates. Meanwhile, Josh tries to figure out the details of his past and re-learn his astral projection ability in time to help his son.

Unfortunately, the script — from Scott Teems, who wrote the poorly reviewed “Halloween Kills” and the even more poorly reviewed “Firestarter” reboot — is too concerned with the series’ blend of supernatural mumbo-jumbo to hook an audience that likely doesn’t remember those films in detail. New characters, such as a college friend played earnestly by Sinclair Daniel, are thinly sketched at best.

While a few of the early set pieces are genuinely scary — if you see this film, I hope you don’t have an MRI scheduled anytime soon — you’ll have checked out by the time we’re wandering around in the astral darkness. While a spinoff is allegedly on the way, I’d be surprised if “Insidious” hangs around much longer.

Until the inevitable reboot, of course. Horror franchises are harder to kill than their own villains.

My Rating: 4/10

“Insidious: The Red Door” is now playing in theaters.