By Letitia Baldrige

Doubleday. 378 pp. $18.95

Letitia Baldrige went to Vassar with Jackie O.

Eventually she became her chief of staff and social secretary for the Kennedy White House. When Camelot collapsed, she moved to New York, where she became an authority on etiquette, built a successful public relations firm and wrote 12 nonfiction works -- most recently "Letitia Baldrige's Complete Guide to the New Manners for the '90s."

Now Baldrige has written her first novel, "Public Affairs, Private Relations." This is a Trump Shuttle kind of story that focuses on fashion, power, protocol, class and style -- none of which has any real emotional content or social meaning. The heroine, Marika Wentworth, is a good-looking, snobby Bostonian widow who runs a public relations firm in the Big Apple but still remains best friends with her college chum, Eve Watson, who now lives in Washington, D.C., because she's the ... First Lady of the United States! This is revealed on Page 2 when Marika assures Eve it was okay to have telephoned her after midnight because "nothing is more flattering than to have an old college pal and one's best friend, who just happens to be the wife of the President of the United States, declare that I am an important part of her life."

Social etiquette is the commanding impulse of this novel. At a White House dinner, our heroine "recognized the French ambassador, several famous media figures, two cabinet officers, the head of the Smithsonian Institution, a champion boxer, two movie stars, three famous corporate CEO's, two senators, two congressmen, a baseball star ..." There are -- of course -- things to be learned from Guest List Fiction. Baldrige gives us tips on how to place personal calls to the White House, how to design successful window treatments, how to dress for a "delicate salmon, white asparagus, and raspberries lunch" at Le Cirque and how to respond if the First Couple pick up their asparagus stalks with their fingers!

There are many such facts for inquiring minds. Official White House dinners require glasses for both red and white wine, as well as champagne and water goblets, which means that "four times 130 guests equals 520 glasses." In official life "one speaks to one dinner partner for the first course and to the other dinner partner for the next course, and then one continues alternating conversational partners at the beginning of each new course." Baldrige poetically personalizes this rule for her protagonist by explaining that Marika "would have Ambassador Tuffier all through the smoked trout and mousse de foie gras en gelee, then Jonathon Scher for the faisan Fontainebleu, Ambassador Tuffier for the salad and cheese course, and Jonathon again for the bombe glacee rustique dessert."

By the time I realized Ambassador Tuffier wasn't a dish, the bombe goes off and Marika falls for rich Jewish Chicago businessman Jonathon Scher, seated to her right. Unfortunately, Jonathon is wearing a gaudy diamond ring that symbolizes the social-cultural differences between the two. Although we're never told if the diamond is worn in pinky position, we know Jonathon won't fit in with the WASPish crowd at Marika's stepfather's funeral and that Marika won't charm Jonathon's mother, who's not big on shiksas -- even well-bred blue bloods.

In this novel, you can tell the good guys from the bad guys by the jewelry they wear. Eventually Jonathon has the diamond removed from his ring and transplanted into a brooch custom-designed for Marika's bosom. Events such as this bump the plot along at a fairly friendly pace despite some dazzlingly stilted dialogue, some infelicitous descriptions ("Le Cirque's aristocratic-looking owner, Sirio Maccioni, swept his eyes around the dining room with the movements of a rapid lawn sprinkler, taking in every table in the room") and a promising, but ultimately empty-caloric detour to Hungary that leaves the reader ... well ... hungry.

Letitia Baldrige is enough of a pro to handle her story elements smoothly, to develop several subplots -- a search for the true identify of Marika's dead father, the affair of Marika's up-to-date tell-it-as-it-is daughter with a macho Italian, the improved sexual relations between the president and his First Lady thanks to Marika's meddling, and the ups and downs of a public relations firm.

In her first-time-out-of-the-gate novel, Baldrige makes good on only half the promise of her title. She tells us lots about public affairs, but precious little about private relations.

The reviewer's most recent novel is "Hot Flashes."