SASHA AND EDIE are this season's literary glamour twins, daughters of the rich, and twice doomed: doomed in their foreshortened years to spin out rebellious and degrading lives in the reflection of unearned luxury, and doomed in death to the gluttonous scrutiny of voyeurs who crave most of all the details of the ornate lives of their parents.

Like Edie Sedgwick, Andy Warhol's suicidal superstar whose family connection earned her an extended biographical epitaph, Sasha Bruce rides piggyback on her family name in death as helplessly as she rode it in life.

Privilege becomes the appropriately ironic title for the biography of this poor little rich girl who slummed through a nether world of creeps and opportunists in blind pursuit of perverse love, even as her glamorous and sought-after parents moved along the fast track of international diplomacy and power politics.

On November 7, 1975, the daughter of David K.E. Bruce, one-time ambassador to France, then to West Germany and later to Britain, whose family arrived in America before the Revolution, was found under a tree on her father's Southside Virginia estate with a bullet through her head. She died without saying by whose hand the bullet was put there, and her death was first ruled a suicide. But when the case was reopened three years later, Marios Michaelides, a Greek who had been her husband for three months, was indicted in Charlotte County, Virginia, for murder. He fled to Greece, where under law he is immune to extradition. (The Greek government has conducted an "inquiry" using the evidence from the Virginia indictment, but has not indicted Michaelides.)

As if to emphasize the ambiguity surrounding Sasha's death, her mother, the elegant Evangeline Bruce, was to tell police that she thought her daughter held the gun, but that her daughter's husband was the murderer.

How could Sasha Bruce, endowed with wit, intelligence, money, and status, come to inhabit such a dark and destructive world? Inevitably, Joan Mellen raises more questions about the barren nature of Sasha's life than she answers, and her inventory of Sasha's cash exchanges tends to pall. But her story is a compelling one, her telling of it lively and ambitious. She asks the right questions and does not pander to the prurient wrong ones.

Sasha, the oldest of three siblings, was born Alexandra, the child of her father's second marriage, and called by the Russian diminutive. He was 48 when she was born, and often seemed a beloved remote grandfather. Though the Bruce name was vintage Early American, David Bruce acquired his wealth through a first marriage to Ailsa Mellon, daughter of Andrew Mellon, the industrial baron. Andrew gave his son-in-law a million 1926 dollars as a wedding present so that he wouldn't be tied to his wife's purse strings. The marriage ended in divorce.

David got to keep the money, and in 1945 he married Evangeline Bell, 20 years his junior, the daughter, stepdaughter, and niece of diplomats. Unlike the shy and withdrawn Ailsa, Evangeline Bruce was gracefully outgoing, a perfect complement to her husband's own diplomatic career. She had a faultless instinct for haute couture, exquisite decor, and good food. Everyone who ought to have been there supped regularly at the Bruce table. Said Arthur Schlesinger Jr. of the Bruces: "(They) used social occasions with great effect."

Though Evangeline Bruce tried to balance her career as a diplomat's wife with her role as mother, her social obligations as she perceived them were relentless. When her husband was appointed ambassador to the Court of St. James's in 1961, Mrs. Bruce decided that it was time to send Sasha, 15, to boarding school. "There is a time in cultural expatriation when children should go home," she said, intending no irony.

But the one thing Sasha never found, according to Joan Mellen, was a home to go home to. Rootless and restless, she died at 29 craving love and a sense of place. At St. Timothy's, a Baltimore boarding school for those with blood of the proper shade of blue (Edie Sedgwick of Edie was a St. Tim's girl, too), Sasha found some solace in a teacher about whom she wove a romantic father-as-lover fantasy. At Radcliffe, she threw herself into "good works" at a school for troublesome boys. She occasionally teased the boys with her sexuality. She popped speed and LSD, and slipped away to sexual abandon in a mad flight from what she called her "genealogical prison."

Despairing of the weak, soft men she found at Harvard, she began searching for a man whom she could fear, to whom she could yield herself in sexual and spiritual submission. She allowed herself to be picked up in bars by a succession of black married men, and seemed genuinely astonished when not one of them leaped at her invitation to him to abandon his wife for her. In London she submitted to humiliation, sexual and financial, at the hands of a lover who bought and sold phony icons; she allowed herself to be "rescued" from him by a man who capitalized on what was left of her fortune and lack of self-esteem.

Sasha's seedy story, as told here, tempts us to blame her family and her unsupervised wealth for her descent into depravity. Born with a subtle intelligence, expensively educated in the proper schools, tutored in the responsibilites of privilege, she was nevertheless left to suffocate under the the weight of affluence and got almost none of the repetitious nurturing that translates to strength of character.

When she died, her father arranged a correct but hasty burial service, scheduling it so soon after her death that her friends had no chance to be there, and prevented a time-consuming autopsyybecause he wanted to keep an appointment with the president the next day in Washington.

The Bruces were prototypical public servants, esteemed for selfless fidelity to a standard of civic responsibility. The question every parent would ask, perhaps as the Bruces asked themselves, was whether this fidelity was bought at the price of a child? Could the depression which tormented most of Sasha's years have been assuaged if someone had tried to understand the precise nature of the torment? Such questions invite easy answers; too easy.

Ultimately the responsibility for her life, like the lives of all of us, rests upon the one who lives the life. Seen in that light, Privilege becomes a morality tale. Though she allowed men to become the agents of her self-destruction, greed and lust were the twin vices she chose to abandon herself to, and if she allowed her lovers to destroy her idealism it was she who chose the men.

"When you're rich and powerful," said her brother, Nicky, "whatever happens to you, you survive it." Sasha did not survive, succumbing to a spiritual death long before the trigger at her temple was sprung by an unknown hand. Nicky was wrong. The rich and the powerful, just like the poor and the weak, must find within themselves a source of something to nourish the spirit, too.