Now that's what I call word-of-mouth

A single mention on a US radio station propelled Jane Mendelsohn's first novel straight into the bestseller charts.

A book that meditates on what could have become of Amelia Earhart - America's sweetheart aviatrix who mysteriously disappeared over the Pacific ocean 59 years ago in July - has become America's unexpected literary summer hit and launched its 30-year-old first-time author, Jane Mendelsohn, on a flight of popular and critical acclaim.

Just as Earhart's romantic heroism captured public imagination, I Was Amelia Earhart has relit interest in the fable of worldly escape: the book, which runs to just 145 pages, is already in its fourth printing since it was published in mid-April and only dropped from No.8 on the Wall Street Journal fiction lists because bookstore shelves have been stripped of copies.

Besides gathering unexpected sales and good reviews, the book has provided its publishers with a lesson in how a single customer can transform an author's fortunes: within days of publication, Don Imus, a firebrand radio shock-jock best known for embarrassing President Clinton at a White House correspondents' dinner earlier this year, began talking up the book after it had been passed to him by his wife who had unearthed it at the back of a Connecticut bookstore.

Soon afterwards the national press caught on and Mendelsohn, who had been rejected by 15 publishers before landing at Knopf, was booked on TV shows ranging from the Today show on NBC to studio interviews on public broadcasting, two Hollywood studios battled to option the story and, da- dah, she's the current literary darling.

"I couldn't even get an agent so it's pretty much a dream come true to have it published, and to have it so well received is kind of amazing," she told me last week at home in New York. "Almost as soon as it came out everything started to go kinda crazy."

I Was Amelia Earhart was inspired by an article in the New York Times in 1992, about a man who thought he had found a piece of the aviator's plane. "I'd always thought she travelled alone but when I heard she had a navigator, the idea of two people flying around the world and crashing seemed full of possibilities."

Taking the facts of Earhart's life as ornamental punctuation for the story, Mendelsohn imagines that, instead of crashing into the sea on the most hazardous leg of her round-the-world flight, Earhart lands her twin-engine Lockheed Electra on an uncharted island reef where she and her navigator, Fred Noonan, enter an afterlife of "splendid isolation" on an island they name "Heaven, as a kind of joke."

Shifting between past and present, first-person narrative and third-person ventriloquy, Mendelsohn offers a delicate meditation on the adventurer's escape from earthbound concerns and it is her intention that their fate is left uncertain. "Whether life is more real than death, I don't know," Earhart muses. "What I know is that the life I've lived since I died feels more real to me than the one I lived before."

The ethereal imagery of the book, which might have failed in lesser hands, is grounded in the immediacy of the author's compressed prose. Mendelsohn, who supported herself writing book reviews for the New York Guardian and Village Voice, took two and a half years in low-rent apartments to fashion a book that, the New Yorker says, has appeared "like a flash of silver in the leaden skies of contemporary fiction".

Raised on Manhattan's Upper West Side she studied English at Yale and decided on a career as a writer after a year studying law. Small and single- minded, she derives her enthusiasm for literature from, among others, Gabriel Garcia Marquez, with whom she shares the technique of sounding a plausibly mythical note while still telling a naturalistic story.

"I wanted it to be doing two things all the time - to be real enough to get lost in as a story, and for the writing to make you aware that it is a fantasy," she says, fixing me with her penetrating gaze."It's supposed to be an awakening on every level, about the possibility of living more than one life."

As she writes, Earhart's only solace is her silver plane and the skies through which she flies. "We spent our days feverish from the flaming sun or lost in the artillery of a monsoon and almost always by the unearthly architecture in the sky." As well as reflecting Earhart's unconventional emotional states, the book mirrors Mendelsohn's own concerns. "I really identify flying with writing so a lot of the time when I am writing about the sky I am also writing about the blank page and the experience of writing."

The first half of the book portrays the aviator as an isolated, unhappy woman in a loveless marriage to "G.P''. - George Palmer Putnam - the publishing scion and her publicist and trapped by her contradictory need for isolation and companionship.

"By the tender age of 39 she was the loneliest of heroines," says Mendelsohn. "She felt as though she had already lived her entire life, having crossed the Atlantic solo and set several world records and she had no one to share her sadness with, least of all her husband." Trapped in her role as a Greta Garbo of the air and forced to take along a navigator (Noonan, a handsome, drunk womaniser) Earhart sets on the most dangerous leg of the flight from New Guinea to Howland Island with careless regard for their safety - she has jettisoned the radio antennae and neither can tap Morse code. "Much later, when I looked back on the flight, it seemed to me that we had been two lost souls in an immense netherworld, travelling toward an arbitrary goal. wondering which of us was more forsaken: the navigator who didn't care where we were going or the pilot who didn't care if we ever got there.

"It was reckless and pretty suicidal," confirms Mendelsohn on her heroine's fateful flight. The Amelia Earhart in my book is very torn. She has a strong wish to escape but she gets too much aesthetic and physical pleasure out of life to kill herself." With the aviatrix lost and Noonan drunk, her beloved Electra runs low on fuel, loses altitude and lands on a small island. The stage set, the aviators are forced to adapt to their abandonment and, in doing so, work off their emotional baggage and draw closer until the only pleasure they know is each other.

Through a series of flashbacks and dreams, through Noonan's lapse into madness, an intense heat wave that prevents thoughts of the future and an apocryphal storm that erases the past, the months (or years) pass until "there is no difference between being rescued and being captured."

Noon prepares dinner and adorns himself with flowers and anklets of monkey hair; Earhart constructs elaborate fires modelled on the Brooklyn Bridge and the Eiffel Tower, writes her diary and watches birds in the lagoon stepping "in and out of the water, delicately, like ladies".

Stripped of control over her world, Earhart shakes off her cold professionalism and ends up paddling in metaphysical lagoons: "It was as if what she had considered to be herself all these years was only a magnified detail of an enormous painting whose composition and narrative she had never before known existed, let alone seen."

What happened to Amelia Earhart and her navigator may never be known. Rumours still persist that they were captured by the Japanese or that they survived the flight only to die of hunger and thirst. "The truth," says Mendelsohn, "is that we have no idea."

I was Amelia Earhart by Jane Mendelsohn is published by Jonathan Cape at pounds 9.99