"The Bolter: The Story of the Wild, Beautiful, Fearless Idina Sackville, Descendant of One of England's Oldest Families, Who Went Off to Kenya in Search of Adventure and Became Known as the High Priestess of the Scandalous 'Happy Valley Set' " has the makings of a great novel (see subtitle). Unfortunately, the book isn't a novel. It's the story of the author's great-grandmother, an aristocratic charmer and scapegrace of the early 20th century whose terror of boredom, desperate need to be loved, and apparent nymphomania led to five failed marriages, endless sordid affairs and the seemingly inevitable loss and ruin of all she longed for.

Idina Sackville's life really was the stuff of fiction. It supposedly gave shape to Nancy Mitford's infamous character "the Bolter" in a series of novels. And Idina was the model for Iris Storm in Michael Arlen's novel "The Green Hat" (the source, in turn, of some of this book's more incisive passages). But, confined to the facts conveyed in letters, interviews and society news stories, Frances Osborne can only give us what amount to reports, observations and some speculation.

The Idina who emerges from these reports is, we are told, fascinating, enthralling, entrancing. And perhaps there is something fascinating about a woman who introduces a rage for bathing in champagne (ugh), conceives of games in which houseguests feel one another's parts through sheets in an attempt to determine bedmates, and abandons her children to run off to Kenya with a man she refers to as "the child."

Fascinating, but not particularly sympathetic. Sympathy does seem to be what Osborne is striving for, telling us now and again how much Idina needed love. What she merits here, however, is pity. And even that is somewhat hard to maintain as she sleeps her way through the white colonists of Kenya, trailing servants and burning through what the author calls the "tiny" sum of 10,000 pounds (earlier said to be "the equivalent of a million today").

"The Bolter" does paint an interesting picture of Edwardian England, its social mores and rigors giving way to the wildness of pre-depression Europe. We get a view of Idina, with her louche peers with names like Cockie and Squashy and Buffles, pursuing their pleasures in a sort of near-hysteria as the world moves again toward war. And we see the white settlers precariously perched above the Rift Valley in Kenya, madly maintaining their civilized British "superiority" as the Mau Mau stir.

But F. Scott Fitzgerald gave us more of the pre- and postwar pathos in a mere short story. And Isak Dinesen (not nearly fast enough for Idina) tells us exquisitely, in "Out of Africa," about being a European settler in Kenya. Jean Rhys' characters, with less money and spunk, take us to the depths of the lone woman of that time trying in vain to trade her company for love.

So, although there's plenty to be had here about who was who, what they wore, where they went and which games they played (appropriately called "stunting"), the real feeling of the time and of a woman like Idina might be better found elsewhere. "The Bolter," finally, does best as an admirable attempt at restoring Idina Sackville to her family.

Ellen Akins is a novelist who lives in Cornucopia, Wis.