It was the best show in town, the society chronicler Dominick Dunne once wrote of Mortimer’s, a brick-walled restaurant at the corner of 75th Street and Lexington Avenue — provided you could get a table.

From this distance, it is not easy either to characterize or even comprehend the appeal of a joint that from 1976, until it abruptly closed after the death of its proprietor Glenn Bernbaum in 1998, occupied a singular place in Manhattan’s social landscape and even beyond it. Generally acknowledged to have been the clubby spot that appears in Tom Wolfe’s “The Bonfire of the Vanities,” Mortimer’s was so unassuming that scenes from the movie were filmed elsewhere because, as Mr. Bernbaum himself once said, “people from the Midwest wouldn’t understand the plainness of the place.”

The décor was at best basic: bare brick walls, schoolhouse lanterns, a curved bar left over from its days as a saloon and bentwood chairs with hard seats the Vogue editor André Leon Talley once complained were “difficult for one’s bottom.” The menu ran to nursery fare like chicken hash, salmon croquettes and creamed spinach, reasonably priced (a hamburger in 1976 cost $1.90) because as Mr. Bernbaum once also observed, no one is as cheap as the rich.

The clientele at Mortimer’s was always the draw, and it was indeed a starry lot, as evinced by “Mortimer’s: A Moment in Time,” a new coffee table book by Robin Baker Leacock, with images by Mary Hilliard, to be published next month by G Editions. The book illuminates a vanished social landscape populated by the moneyed, well connected, celebrated and sophisticated, a group that fitted Marlene Dietrich’s long-ago observation about New Yorkers that they are constantly hungry for everything except food.

By broad consensus, Mr. Bernbaum, a natty former garment industry executive who, as part of his post-retirement second act, bought an Upper East Side building, was a curmudgeon. With no background in the hospitality business, he installed his restaurant on a corner, wedged between a Catholic church and two now-defunct gay bars and proceeded to run it, effectively, as a private preserve.

“It was a club, basically,” the writer Bob Colacello said in an interview.

A man of contradictions, Mr. Bernbaum was rude and kind, distant and warm, sad and often cuttingly funny. “Cerberus of the Upper East Side,” is how Peter Bacanovic, a tech executive and longtime Mortimer’s habitué, recently characterized the man. Yet, unlike the hound of Hades, Mr. Bernbaum ferociously guarded the gates to his demesne against those he deemed the unwashed social dead, cosseting and fawning over the favored ones who made it past the gate.

It is instructive to reflect on how small, in the predigital world, was that group of largely self-selected elite that seemed to rule New York. Capital “S” society thrived in those days. Fashion was effectively controlled by John Fairchild, the snobbish publisher of Women’s Wear Daily. A tight group of “confirmed bachelors” like Mr. Bernbaum, Bill Blass and the socialite Jerry Zipkin — who probably had a better hotline to the Reagan White House than did members of the Joint Chiefs of Staff — subtly exerted their power on the social scene. Ornamental young debutantes capered about in Christian Lacroix pouf dresses. And the ladies who lunched really did so — if you can call a meal three bullshots and a Craven A cigarette smoked in a Dunhill cigarette holder.

That is how the editor, novelist and one-time gossip columnist William Norwich described his introduction to Mortimer’s soon after its opening in 1976. Mr. Norwich first visited the place as the guest of a friend’s mother and returned through the years, drawn, as most of its patrons were, by the eye-popping people-watching.

Invariable on Sundays, 1B, a table to the right of the window would be occupied by Diana Vreeland. Nan Kempner sat nearby and so, too, did the fashion plate and philanthropist Judith Peabody, crowned with her signature bouffant nimbus. On any given day, alone or in combination, as Mr. Dunne noted in Vanity Fair, one was likely to spot the heiress Gloria Vanderbilt, Barbara Walters, Jacqueline Onassis, Estée Lauder, William S. Paley, Fran Lebowitz, Henry Kissinger, Claudette Colbert, Katharine Graham, Mike Wallace, Lord Snowdon or Greta Garbo.

Few among these A-list movers and shakers survive any longer in the collective memory, and so so it is as a document of a vanished time that the book earns its hefty cover price of $85.

Perhaps one way of viewing Mortimer’s is as the sum of New York society in the days “before P.R. ruled nightlife,” as Ms. Leacock said from her home near Palm Beach, Fla. “In my mind, P.R. people changed the landscape of going out in the evening because you have to be on a list, and the list did not even exist then.’’

Or if it did, it was primarily in the head of one sniffy, eccentric and autocratic restaurateur, a man who never took reservations but who did, of course, as he told Vanity Fair, scrupulously run a joint where we “take care of our friends.”