"Insurgent" is a sequel to the 2014 film "Divergent," starring Kate Winslet and Shailene Woodley. It raises the stakes for Tris (Woodley) as she is on the run and searches for answers in the ruins of a futuristic Chicago. (Lionsgate)

“Tell me: Do you appreciate irony?”

That’s the question put to Tris (Shailene Woodley), the heroine of the latest installment in the “Divergent” film saga, “Insurgent,” by the film’s villain, Jeanine. Rendered by Kate Winslet as a caricature of such steely intelligence that she looks like the product of a sheet-metal plant, Jeanine doesn’t mean it this way, but her question highlights a central irony of the film. It’s one that’s even more prominent in this second chapter of the sci-fi trilogy — which is set in a dystopian Chicago where people have been sorted, like machine parts, into five personality-based “factions” — than it was in the first.

The irony is this: It is the Erudite, the brainiac faction of which Jeanine is supreme leader, that administers and defends this harebrained scheme.

There, I’ve said it. The very foundation of the “Divergent” world is built upon the stupidest organizing principle ever. Whose cockamamie idea was it that all people can be classified by a narrow predilection for brains (Erudite) or heart (Amity) or bravery (Dauntless) or honesty (Candor) or self-sacrifice (Abnegation)? (And why no Comedy faction? Where do all the class clowns go?) Don’t expect an answer in this movie; series author Veronica Roth didn’t get around to figuring one out until the third book, “Allegiant,” which is being released as two separate films in 2016 and 2017.

Four (Theo James), Peter (Miles Teller) and Tris (Shailene Woodley) return for the second movie in the “Divergent” series. (Andrew Cooper/Lionsgate)

The mere presence of Divergents (people, like Tris, with affinity for more than one faction), not to mention the sizable underclass known as the Factionless (misfits who, for one reason or another, have flunked out of their designated cliques), should serve as a red flag that something isn’t working.

But never mind. The Kafkaesque absurdity of the situation is at least recognized by Tris, if not by Jeanine. In response to a rebellion led by Tris and her boyfriend, a fellow Divergent known as Four (Theo James), Jeanine has come to believe that the solution to what she calls the “Divergent crisis” is contained in a locked time capsule that has been left by the founders of this kooky world. Ironically, the box can only be opened by a Divergent who is capable of completing a series of virtual-reality tests, or simulations, utilizing skills from each of the five factions.

Paging Tris, to the white courtesy phone.

The most cinematic of these sims, calling on Tris’s derring-do, involves rescuing her mother (Ashley Judd) from a burning building that is flying through the air. And yes, “Divergent” fans, Mom did die in the last movie. The simulation is not real. (It is, however the one and only reason to see this movie in Imax 3-D. The special effects in this scene look particularly good on a screen the size of my house.)

Less effective is the film’s ability to make us care about any of this. Although Woodley is adequate at emoting — Tris being something of a basket case of guilt, self-loathing and teenage hormones — many of the other characters here are, by definition, one-dimensional. “Thank you for your candor,” chant the members of Candor, like robots, after administering a truth serum that forces Tris to confess to killing a friend in the first film.

Talk about irony. “Go with happiness,” is the mantra of the back-to-nature Amity faction, whose members shuffle around morosely, like members of an agrarian therapy group for depressives.

There is, however, a certain urgency to the action that will prevent most people from noticing the film’s flaws. And there are several nice performances, especially by Miles Teller, returning as Tris’s Dauntless nemesis Peter, and new cast member Naomi Watts, playing Four’s Machiavellian (and factionless) mother. Shifting loyalties and ambiguous motives keep the viewer off balance in a good way.

Not so great is the way the film ends, delivering a frustrating resolution — yes, the one contained in that lockbox — that only deepens the mystery behind the crazy faction system. Rather than offering a teaser to the next film, this lack of closure left me feeling like the waiter had whisked my plate away before I was finished.

“What now?” Tris wonders aloud, as “Insurgent” grinds to a premature halt.

You know what, sister? I’ve been running alongside you for two movies now, waiting for an answer to that question. But with two more years to the finish line, I’m running out of patience, not to mention breath.

PG-13. At area theaters. Contains violence, sensuality and brief coarse language. 119 minutes.