"Trio," the story of the lifelong friendship of Oona Chaplin, Carol Matthau and Gloria Vanderbilt, is an exasperating demonstration of how to turn a silk purse into a sow's ear. Think of it: Eugene O'Neill's daughter who married Charlie Chaplin, the rags-to-riches lass who married William Saroyan (twice) and later Walter Matthau, and the poor little rich girl herself who married Leopold Stokowski and three others, formed an intimate circle -- charmed, I'm sure -- that spanned five decades and was the toast of American high society. You can't lose with their story. Or can you?

Truman Capote was notoriously successful in using the hilarious luncheon conversation between Carol Matthau and Gloria Vanderbilt as the taking-off point for barely fictionalized tales of the rich and famous in "La Co te Basque, 1965." In this infamous short story -- the best of the published parts of the unfinished "Answered Prayers" -- Capote saw Matthau and Vanderbilt as "charmingly incompetent adventuresses" who were so far into the trappings of American royalty that only their fast sass and unwavering loyalty to each other kept them sane.

Author Aram Saroyan, son of Carol Matthau and William Saroyan, probably wanted to ring a variation on the Capote theme, picturing the women as madcap heiresses -- the kind Katharine Hepburn used to play in the '30s -- without turning the trio into Capote-like sacred monsters. Instead, the diplomatic, lighthearted Saroyan ends up killing his mother and her friends with kindness. Presented as a series of short vignettes and discreet conversation pieces -- post cards from the past -- "Trio" traces memories of the three women from 1941 to the present, through marriages, divorces (not their fault) and spouses' deaths. That's a lot of ground to cover, and the perplexed reader by the end might well feel cheated by Saroyan's elliptical style.

"Trio" leaves nothing but questions. Do the women think it is a coincidence that they married men much older and more famous than themselves? Why didn't Gloria Vanderbilt ever speak to her friends about her custody battle? (Didn't they ever ask?) Why is William Saroyan presented as "The Phantom of the Opera" while Carol Matthau seems to be playing in "The Passion of Joan of Arc"? (What was their problem?) Why did Vanderbilt's marriages fail? (Did she ever confess to friends, "They married 'Gloria Vanderbilt' and got me"?) Why is Carol Matthau described constantly as "witty" when she says nothing funny in 256 pages? (One has to read "La Co te Basque, 1965" for examples of Matthau's humor.) If Carol Matthau suspected that Vanderbilt was condescending toward Carol's marriage to Walter Matthau, how did Carol feel about Gloria's marriage to the then-lowly TV director Sidney Lumet? How bad is Oona Chaplin's self-imposed exile since her husband's death, and what are best friends Carol and Gloria doing about it?

Aram Saroyan instead offers the trivial: a 20-page description of the time Oona and Carol were stood up at a Brown football game (life as the school of hard knocks); Truman Capote peeping through a transom at a nude Carol; Kenneth Tynan's elaborate pursuit of Carol ("I find you divinely beautiful and witty, and I want to marry you"); Gloria and Carol's amazement at one of their California parties "setting some kind of local record" (smart Gloria had spiked the punch!).

The women's conversations are cluttered with such inanities as "I mean the way (Gloria) loves you makes me love her" and -- constantly -- "You are so divinely beautiful," to which the response is invariably, "Oh sweetheart, please. You're the beauty." We find Walter Matthau calls Carol "pussycat," Carol and Gloria call each other "sweetheart" (27 times), and everybody calls everybody else "darling" (108 times -- it's the Manhattan mantra). When a young man tells Carol, "You only like famous people," Carol's apocalyptic retort is, "They're all terrific, and you stink." After she sticks out her tongue at him, the young man moves on, "definitely out of his depth."

None of this is used for a satirical effect. If the tone were lightly self-mocking, the women might have come off less cloyingly vain and artificial. And Aram Saroyan's unwillingness to get into anything potentially unpleasant turns the trio into something not recognizably human. (You've heard about being out of your league, but out of your species?) The "gossip" here is hardly news: Gloria taking LSD under a doctor's care, a depressed Carol collecting sleeping pills, Oona fighting off J.D. Salinger -- all of these have been written about before with much more authority and poignance.

The women tell each other constantly how much their friendship means to them; the problem is that the author fails to dramatize it in any realistic or cohesive way. Friendship is much more than brushing cheekbones in greeting. Intimate, long relationships involve mess, humor, irrational loyalty, and yes, a perverse enjoyment of each other's naughty habits. In "Trio," the rich are different from you and me: They're just plain dull, darling.