Happy Endings.

Happy Endings. Sally Quinn. Simon & Schuster, $22. William Roswell Grey 111, the President of the United States, gets assassinated while dining at the home of one of Washington's most ambitious hostesses. Sadie, his sex-starved Southern widow, indulges in a passionate fling with Desmond Shaw-the dynamic, roguish editor of a national news magazine and unbeknownst to him, gives birth to his son. Unfortunately, Des is also the lover and eventual husband of Allison Sterling, the best reporter on the nation's most powerful newspaper. Glamorous and tough, she finds herself yearning for more in her life than just a daily deadline.

All this mess is from Sally Quinn's new novel, a sequel to Regrets Only, which continues the saga of low jinks among Washington's lofty people. Quinn's characters are on the city's fast track: They're clever and brittle as they party in the White House, vacation in plush resorts, and power-lunch at Nora and Bice. But when Des and Allison are forced to cope with the death of an infant daughter and, as a result, the breakup of their marriage, the tone suddenly softens. Des, a lapsed Catholic, turns to God for help, while Allison battles loneliness and despair.

Their heartbreak and mourning are affecting: Here, for the first time, Poison Pen Quinn shows she can write a good, old-fashioned weepy novel. Nevertheless, it is as a savage observer of D.C.'s peculiar manners and morals that Quinn is at her best. "Power is everything," she rightly observes. If you can't be president then the name of the game is to be as close as possible to whoever the son-of-a-bitch is." And this novel serves as a fairly accurate indicator of where today's political power really is-and isn't.

>"In the old days there used to be a number of extremely rich women, widows or wives of establishment men, who acted as catalysts. They held salons where members of the establishment could get together and socialize, compare notes, exchange political gossip, commiserate, collude. There are almost none left. . . . The few that are are looked upon as anachronisms."

>"The embassies were essentially dead. They just didn't matter. They just didn't matter anymore since shuttle diplomacy, television, direct dial, and the fax had replaced the need for ambassadors."

And so on. Even the prima donnas of journalism do not escape her lethal scrutiny. Among the many intimate personal moments, there appear enough newsroom slugfests, behind-the-scenes preening, leaks, and gossip to satisfy the most ardent news junkies, and to keep them guessing who's who. But in the end, Happy Endings-which, incidentally, has one -is a sensitive and substantive book about relationships, revealing a kinder, gentler Sally Quinn. What makes it fun, however, are the vestiges of the vicious old one.

-Sandra McElwaine