For anybody who watchers “Gotham,” one look at David Mazouz, who plays Cameron, the kid who’s possessed in “Incarnate,” will tell you that Brad Peyton’s movie has been sitting on the shelf for quite a while. As Bruce Wayne in the Fox series, Mazouz has grown into a tall, rangy adolescent; in this “Exorcist” semi-ripoff, he’s at least a foot shorter and looks about ten.

Of course, a movie that’s been kept in mothballs for a few years isn’t necessarily bad, but there is usually some reason for a lengthy release delay. In this case the cause is obvious: a horror movie that’s not remotely scary or disgusting is hardly going to draw a crowd nowadays, so despite a fairly solid cast, a twist on the usual “Exorcist” formula and a director who had a hit with “San Andreas” (to which he’s now making a sequel), “Incarnate” is a tedious dud whose lack of gore and thrills will certainly doom it with the genre crowd.

The script by Ronnie Christensen (“Passengers”) begins with Cameron moving into a ratty apartment with his recently-divorced mother Lindsay (Carice van Houten). He’s jumped by a homeless person who sneaks into the place—and who is apparently possessed—and in the process of their struggle, the entity abandons the derelict and takes over the kid, who thereupon snaps his attacker’s throat.

Cut to what turns out to be a sequence in which Dr. Seth Ember (Aaron Eckhart) has entered the subconscious of a possessed man (John Pirruccello) to “evict” the entity that has taken him over. He’s a scientific sort of exorcist, who works with a couple of aides, Oliver (Keir O’Donnell) and Riley (Emily Jackson). They watch over him while he enters his subjects’ minds to free them from the pleasant hallucination with which the entity keeps them under control, ready with drugs to bring him out of his trancelike state if his vitals begin to spike. Though during these trips into the subconscious of the possessed Ember is a strapping, clean-shaven fellow with the use of his legs, in reality he’s a disheveled guy with a scraggly growth of beard, confined to a wheelchair as the result of an auto accident.

His condition explains Ember’s obsessive work: the car crash was an intentional assault on him by a drunk driver named Maggie, who was possessed by an entity that recognized his ability to perceive parasitical beings such as itself and took the opportunity to cripple him and kill his wife Anna and young son Jake (Karolina Wydra and Emjay Anthony). Ember now does his exorcisms (or evictions, as he calls them) in hopes of finding “Maggie” and annihilating the entity in revenge for his losses.

Ember has no respect for the Catholic Church, but nonetheless takes on Cameron’s case at the urging of a Vatican representative (Catalina Sandino Moreno) after Felix (Tomas Arana), an old friend in the church’s exorcist brigade, assures him that the entity possessing the boy is indeed “Maggie.” That will lead to prolonged sessions in which Ember confronts the lad, who sits in his room making malicious faces and speaking in a creepy voice, and enters his subconscious, in which the kid is dreaming about having some quality time with the entity, which has disguised itself as his now-absent father Dan (Matt Nable).

How things go from this point is pretty much incomprehensible, since at some points in the last thirty minutes you might find that the plot goes into overdrive following the dictum of Warren Beatty’s Howard Hughes movie—rules don’t apply: even the feeble logic the script has attempted to sustain for an hour or so is chucked out the window in favor of twists that are random attempts to surprise. Suffice it to say that Ember eventually faces off against the “Maggie” entity one-on-one, with only minimal impact. And though Christensen clearly intended to break out of the tired “Exorcist” template, he falls back in with the Blatty-Friedkin model too often, from the premise of the exorcist and the “demon” having had prior contact to the self-sacrificing decision the protagonist takes in the end.

Still, one has to appreciate the effort to tweak the formula, even if the result isn’t terribly successful. And one has to admire the way that Eckhart flings himself into the role of Ember, although it’s hardly worth the effort. (He attempted to bring “I, Frankenstein” to life too, with a similar outcome.) Perhaps one of the attractions of the movie for him was that he gets to best a pro wrestler, Mark Henry, who plays a bouncer in an early scene; his presence is explained not by any acting ability, but the fact that the WWE was one of the production partners. Young Mazouz grins malevolently and lip-synchs the dialogue spoken by some evil-voiced substitute well enough. Everyone else in the cast is adequate at best; some appear to have had their lines imperfectly dubbed, though perhaps that’s an impression caused by shoddy sound recording. The overall production is certainly threadbare, with murky images courtesy of cinematographer Dana Gonzales.

One must, however, praise the work of editors Todd E. Miller and Jonathan Chibnall, not for making much sense of the footage but for trimming it down to barely eighty minutes, not counting the closing credits. There’s a place for a picture like “Incarnate,” but it’s really on the SyFy Network, and in its current form it will easily fit into a two-hour slot on that channel. Its brevity will, moreover, surely be some solace to those who see it in what will be a mercifully short theatrical run.