Mary Steenburgen, Jane Fonda, Diane Keaton and Candice Bergen in “Book Club: the Next Chapter.” Fifth Season/Focus Features

A movie like “Book Club: The Next Chapter” might as well be reverse-engineered to plunge a self-respecting critic into an existential crisis. As art, this sequel to the surprise 2018 hit – a giggly, feather-light mom-com starring Jane Fonda, Candice Bergen, Diane Keaton and Mary Steenburgen – is borderline indefensible. Directed by Bill Holderman from a script he co-wrote with Erin Simms, this choppily paced, tonally uneven series of corny gags and heartfelt girl talks has the brightly lit, banal aesthetic that signals Hollywood at its most lazily mediocre.

And yet. As such recent films as “Ticket to Paradise,” “A Man Called Otto” and “80 for Brady” indicate, there is a place in the cinematic firmament for just this kind of shallow but essentially harmless escapism. More to the point, “The Next Chapter” performs at least one act of distinguished public service in providing one of the screen’s most talented comediennes a too-rare chance to share her sublimely dry wit and flawless timing yet again.

That gifted artist is Bergen, of course, who began her career as a thinking man’s sex symbol only to reveal later in life that she had the wiseacre instincts of a borscht belt pro. In the “Book Club” movies, she plays a judge named Sharon, who as “The Next Chapter” opens is having a Scotch and struggling with the titular group’s Zoom meetings. As a look back at the beginnings of the pandemic, the opening sequence has a wistful, nostalgic air – everyone thinks the lockdown will last a couple of weeks – and it explains the longish gap between installments: Finally, with the travel bans finally lifted, Sharon and her friends Diane (Keaton), Viv (Fonda) and Carol (Steenburgen) are going to Italy, with the stated purpose of celebrating Viv’s upcoming marriage to her lost-then-found love, Arthur.

Diane Keaton, Jane Fonda, Candice Bergen and Mary Steenburgen in “Book Club: The Next Chapter.” Riccardo Ghilardi/Fifth Season/Focus Features

It’s something of an inside joke that Arthur is played by Don Johnson – whose daughter Dakota starred in the adaptation of “50 Shades of Grey,” the novel that the “Book Club” ladies were reading last time. (This year’s inspo is Paulo Coelho’s “The Alchemist,” references to which are forced into the dialogue like so much soppressata.) It’s also telling that, to find a believable love interest for Fonda, the filmmakers had to find a man several years her junior: At 85, she still looks smashing, deploying her lithe physique with dancerly grace and precision, and proudly showing it off during a fizz-fueled wedding-dress montage. Viv, a lifelong singleton, harbors gnawing doubts about matrimony, as does Diane, who is still with Mitch (Andy Garcia), the yummy guy she met five years ago. Carol, her Los Angeles restaurant a COVID-era casualty, now pours all her energy into controlling her health-challenged husband, Bruce (Craig T. Nelson). The conflicts of these prosperous, privileged women of a bangin’ age are decidedly low-stakes, even when “The Next Chapter” piles one trivial crisis on top of the last.

Plotty, preposterous and – let’s be honest – more than a tad patronizing, “The Next Chapter” doesn’t deviate from a familiar playbook of similarly frisky wish-fulfillment fantasies: It’s “80 for Brady” without the bedazzled jerseys and Patriots patois. Instead of promiscuous NFL product placement, we get touristy scenes in Rome, Venice and Tuscany, accompanied by barely believable oohs and aahs suggesting these well-heeled dames have never tasted prosecco before (or met a risque meatball joke they didn’t like).

You don’t have to suspend disbelief to enjoy the cheerfully ersatz world “The Next Chapter” inhabits as much as jettison it entirely: “White Lotus” fans might find themselves longing for Jennifer Coolidge to crash the proceedings on a Vespa, her Monica Vitti scarf flowing. Then, it’s simply a matter of accepting the scant but undemanding pleasures of watching these accomplished, preternaturally appealing actresses claiming their rightful space on the big screen, albeit with material that doesn’t nearly do them justice.

That goes double for Bergen, who as in the first “Book Club” gets most of the laughs by way of wry, sarcastically muttered asides. Alongside her more fashion-forward co-stars, she’s styled to make Sharon look as frumpy as possible, right down to the nerdy fanny pack she displays over her sensible stretch-knit khakis. It’s only during one of the film’s more amusing sequences, when Sharon has a mid-canal fling with a handsome man she meets in Venice – played with silky charisma by Hugh Quarshie – that “The Next Chapter” reveals the truth, which is that, when she’s allowed to be, Bergen is just as hot as ever.

So, by the way, is Giancarlo Giannini as an Italian police officer who becomes Sharon’s teasingly grouchy nemesis. Even amid the corny jokes, awkward segues, forced conflicts and predictable resolutions, Bergen and Giannini manage to develop a low-simmer chemistry between the insults. Perhaps in future editions, that frisson can blossom into something more than a footnote.