Gloria Vanderbilt, a headline-grabber all of her life, is 85 now and still in the game.

Her latest novel, “Obsession: An Erotic Tale,” is a lascivious little number bound to set tongues wagging, once again, over the woman first known to the world as “Little Gloria,” America’s “poor little rich girl.”

Here, Vanderbilt boldly visits the bedchambers of the wealthy Priscilla and Talbot Bingham, and also of Talbot’s “permanent Maitresse,” Bee, and of the exotic bordello from which Bee comes — the Janus Club, where the “goddesses” often wear full skirts that, Talbot sighs, beckon to “heaven underneath.”

But if “Obsession” at first seems a prurient little read—or a cruel fantasy for adults — it soon evolves into a clever psychological puzzle. One that Vanderbilt clearly wrote with tongue in cheek and a twinkle in her eye.

First, we have Talbot — a renowned (and controversial) architect married to the frigid Priscilla, whom he nonetheless loves while having no qualms about finding “heaven underneath” elsewhere.

Then we have Priscilla — a devoted, somewhat silly creature who pretends at passion and, after confiding in her physician about this, is told: “You love each other. Talk to Talbot about it.”

“But to do so would be inconceivable,” decides Priscilla. “It was too late. The lie was mid-sea, in full sail. And it worked.”

We don’t have Bee (who we learn is a mirror image of Priscilla) until after Talbot suddenly dies. He suffers a heart attack, during his and Priscilla’s 10th anniversary gala at their estate, the architectural wonder “Talcilla,” on the Eastern Shore of Maryland. In her grief, the unsuspecting Priscilla enters Talbot’s private work chambers, finding the letters she wrote to him over the years — and the letters Bee wrote to him from a place called Akeru in Montecito, Calif. Shocking letters! Titillating! Graphic!

At first, Priscilla tries to think calmly:

“How like (Talbot’s) genius to come up with a solution so as not to let the hassles our separation would involve affect his sacred art — a Maitresse with the infuriating name of Bee to replace what I could not give him.

“But the letters? Are they left in the box among mine, stamped with an invisible tete-beche [upside-down stamp] for me to find as rebuke? Or a farewell message that in spite of it all, because he chose one who resembled me, I was his true love? No — probably it simply amused him to create a paradox that might (to some) define a possible truth.”

And so the obsession begins, with Priscilla on the East Coast reading and rereading Bee’s letters, thinking and dreaming only of Bee — and, as “Obsession” develops, with Bee on the West Coast thinking and dreaming only of Priscilla.

The twain of course shall meet. In fact, perhaps they always have been one, with Bee dormant in Priscilla — Talbot, in dying, giving Priscilla her sexual self. But we are never told, nor should we be.

Replete with symbolism, “Obsession” offers not only the Talcilla home (and logo) for Priscilla but the castle “Akeru” for Bee, Akeru gods being, in Talbot’s words, “supernatural lions. . . two-faced Sphinx, a sort of animal Janus.” Like the club. Plus, Bee’s letters are stamped with that “invisible tete-beche. . .”

In short, “Obsession” is great fun — a tale often told by Vanderbilt in the lyric cadences of a “Just So” story by Kipling, with all the exotica of an “Arabian Night”; a summer bon bon complete with whips, veils, lotions, potions and Kama Sutraworthy uses of vegetables and flowers.

All but one of the Seven Deadly Sins (sloth) is represented here, and Vanderbilt, in her lifelong way, has pulled off another splash in otherwise proper waters.

Once the child in a famous custody suit fueled by the fortune left to her by her high-society father, Vanderbilt has long made her mark as an artist and designer as well as author. She is also the mother, by her fourth husband, of CNN’s Anderson Cooper.

In writing “Obsession,” after her tell-all memoir “It Seemed Important at the Time,” she hardly seems a socialite in her ninth decade.

One suspects this is just what she intended.

Karen Brady is a retired News columnist.

Obsession: An Erotic Tale

By Gloria Vanderbilt

Ecco,

144 pages, $16.99