Or more accurately, “Deficient.” The first part of Robert Schwentke’s filmization of the third (and final) volume in Veronica Roth’s popular YA trilogy—divided, as has become customary with such fare ever since “Harry Potter” pulled off the trick, into two movies to increase boxoffice receipts—departs from its overarching “Divergent” supertitle by being a thoroughly conventional, curiously tedious halfway wind-up. Insofar as the CGI goes, It’s also pretty chintzy-looking.

The essential problem with “Allegiant” is that it’s basically a fill-in-the-boxes affair, assiduously ticking off each element of what by now has become a standard formula for these kinds of movies (and, in the process, ticking off the viewer as well, though in a divergent way). So we reunite with Beatrice “Tris” Prior (Shailene Woodley), the unclassifiable girl in the faction-controlled community of post-apocalyptic Chicago. In the initial two installments she’d seen her parents’ Abnegation faction wiped out, succeeded in finding a handsome fiancé in hunk Four (Theo James) of the Dauntless faction, made friends with the Amity faction headed by Johanna (Octavia Spencer), faced off against unreliable Peter (Miles Teller), once of the Candor faction, and—helped by a factionless group headed by Evelyn (Naomi Watts), who just happened to be Four’s estranged mother—foiled the coup plotted by Janine (Kate Winslet) of the Erudite faction, to which her brother Caleb (Ansel Elgort) belonged.

Now our typically spunky heroine is faced with a new challenge. When Evelyn proves as dictatorial as Janine had been, Tris determines to save her brother from execution despite his past misdeeds, and sets off with him, Four, Peter and ally Christina (Zoe Kravitz) into the wilderness beyond the city’s surrounding wall, despite Evelyn’s prohibitions. So we get first a Great Escape sequence, complete with the intrepid group using ropes and grappling hooks to mount the wall, Adam West “Batman” style, and escape to the outside despite the pursuit of Evelyn’s minions, who look a bit like baby-faced versions of “Mad Max” villains. Then there’s a trek through a desolate wasteland that serves up blood-red rain, which comes across like a retread of the desert sequence from “The Scorch Trials” section of “The Maze Runner.”

Then the picture lurches into yet another tale about authority figures who can’t be trusted, as the four are, after being painfully cleansed of the poisonous toxicity in their bodies, taken to a modernist encampment on the site of Chicago’s old O’Hare Airport ruled by the supposedly benevolent but sneaky-looking David (Jeff Daniels). He reveals the background of everything the previous films had covered: the weirdly divided society of Chicago was an experiment designed to test whether the destructive result of genetic fiddling on humans could be somehow reversed. Tris, who alone among the thousands of Chicago residents is genetically pure (as the result of the self-sacrifice of her mother), will supposedly be used by David to convince the governing Council of the Pure to intervene in the city of The Damaged, where the forces of Evelyn and Johanna are about to engage in a war over the former’s brutal tactics.

But while Tris goes along with David’s avuncular promises, Four, who’s been assigned a more tactical role in the new society, discovers that the ruler’s ostensibly compassionate goals are far from good: David’s army has been kidnapping children from the residents of the “Fringe” wasteland and, using a memory wipe, transforming them into docile followers. And when Four and then Tris, Caleb and Christina, along with Matthew (Bill Skarsgard), an aide of David who ultimately sides with them, attempt to prevent him from using the gas on the entire city with Peter’s help, much mayhem ensues.

The turn in Roth’s narrative toward a parable of the dangers of genetic manipulation and eugenics is troubling in itself, but it’s made more unpalatable by the cavalier way in which it’s treated. Explanations are in very short supply, and when they are attempted they render the premise of the original “Divergent” even more idiotic than it seemed at first. Tossing in a further subplot about intrusive surveillance makes the entire scenario feel all the more crudely manipulative when taken within the context of today’s concerns on the subject.

Still, “Allegiant” suffers not only from its basic theme and structure but from ineptitude in execution. The script is sloppily shaped, and the direction lackluster, while the effects are second-rate, with the matte work in the “Fringe” sequences as bad as what viewers endured in “Fantastic Four.” And the acting is perfunctory. Woodley, who once evinced such promise, makes an even more pallid and simpering heroine than before, while James is just the same impassive hunk. (Their amorous moments together certainly strike no sparks.) Elgort is merely bland, and Teller’s smarmy shtick has grown stale. Usually reliable performers like Watts and Spencer are stuck in thankless, one-note parts that make their final scene of abrupt reconciliation truly ludicrous. As for Daniels, he suffers an even worse indignity when he’s forced to scream “No!” like a cartoon villain as his final dastardly stratagem is defeated by our heroine (though, it must be said, in a way that makes no sense at all).

The “Divergent” series got a bit of a bounce in the second installment, which was somewhat of an improvement over the first. But anyone hoping the upward trajectory would continue will be gravely disappointed. “Allegiant” is as poor as the first movie in the series, and the stage it sets for a fourth go-around is not a promising one.