There was magnetism in those dark, flashing eyes; her bearing was majestic, her smile brilliant. She had the ability to fascinate an audience the bend it to her will, put it in touch with its deepest and darkest feelings. Maria Callas -- one of history's greatest singers -- began as a poor girl in New York, feeling ugly and unloved and determined to make the world applaud. The world obeyed, but it could not make her happy. Only one man could do that and he was one of the richest men in the world. Later, he abandoned her for Jacqueline Kennedy, regretted it, reportedly began divorce proceedings and died before they were finished.

Callas became a legend more stormily operatic than any of the roles she sang -- and that was the problem for Arianna Stassinopoulos, the singer's biographer. "It took three years -- much longer than I had expected," says Stassinopoulos. "The last year was the one that made all the difference, and by the end I was feeling like a detective. The point comes where you know things before you really know them, and then the job is to track down the evidence and prove them."

The result of her work, "Maria Callas: The Woman Behind the Legend," promises to be one of the year's most spectacular biographies and is being made into a film. She did it with hard investigative work, but also with a dream.

Dreams are a traditional source of information on dark, closely kept secrets in Greek legend -- and although her subject was modern, Stassinopoulos was working on a Greek legend. The revelation that first came to her in a dream was that Maria Callas had an abortion in London on the insistence of Aristotle Onassis, the father of the unborn child.

"I woke up one morning having dreamed of her," Stassinopoulos recalls. "I dreamed of her often while I was working on the book, but after this dream I woke up knowing that she had an abortion. I had no evidence at all; that came later. I was talking to one of her friends, about one of her visits to London, and I asked, 'Was this the time when she had the abortion?' She asked me, 'How do you know about that?' and I said the usual thing about respecting the confidentiality of my sources, and then she told me all about it because she thought I already knew. And I did, of course, but I couldn't prove it. You can't put your dreams in a serious biography."

But dreams -- even dreams backed by hard work -- were not enough to get close to Callas, a subject that was attracting dozens of writers. Stassinopoulos also had two extraordinary strokes of luck. First, she was being turned away at the door by the singer's mother when a neighbor fainted in the street. While they were working together to help, they became friends, and the legend hiding the real Maria Callas began to crack. Then, Stassinopoulos managed to win the confidence of Callas' godfather, to whom Callas had written at least three times a week throughout her career, and he gave her access to the letters.

That's what makes this biography different: the backstage detail. Everyone knows the big scenes that were played in headlines: the way she left her mother in Mexico City, as soon as she knew she would be a star, and never saw her again. The bitter court battle for separation from her husband, Giovanni Battista Meneghini. The months spent cruising with Aristotle Onnassis on a yacht named his first wife; the competition with Jacqueline Kennedy and the crushing defeat when Onassis married the president's widow.

And opera lovers know the big scenes where an opera house served as the stage setting: the spectacular audition at the Metropolitan when she was completely unknown, was offered two leading roles and turned them down.

The feuding with the directors of the Metropolitan and La Scala.

The battles with rival soprano Renata Tebaldi, in which words were thrown like daggers.

The spectacular return to La Scala, after she had been booed off the stage, when she won the audience back, held it in the palm of her hand for five performances, and then dropped it -- leaving, never to return again.

The death, alone in her Paris apartment with her pet dogs and two servants.

The will she never signed, which would have given her $12 million estate to her servants. The long litigation for the money between the two people she had most decisively rejected in her life -- her husband and her mother. These are all more or less familiar, but through heavy investigative reporting Stassinopoulos is always ready with fresh details.

Dreams -- the dreams of stardom that drove Maria Callas -- are a major element in this biography, and they are the ingredient obviously pushing it toward the best-seller lists. The story, as Stassinopolulos notes in her introduction, is "both tragedy and fairy tale." It is also a Horatio Alger story, in spite of its unhappy ending. Through pure determination, Callas made herself one the leading singers in the history of opera -- one of the few singers who actually changed operatic history by introducing a new set of performance ideals and reviving a repertoire that was nearly dead.

Stassinopoulos was 10 years old when she first saw Maria Callas in August of 1960. She was one of 20,000 spectators who saw her perform Bellini's "Norma" in the ancient outdoor Greek theater at Epidaurus, and the memory never left her. It was fascination at first sight, and the fascination deepened when she began to work on the biography 17 years later, shortly after the singer's death. "I began with deep respect and admiration for what she did and what she tried to become," Stassinopoulos says in the introduction to the book. "I ended by loving her." That love is the chief weakness of the book, which is unashamedly partisan, but also its greatest strength. Because it was so evident to those she talked with -- as it still is -- Stassinopoulos was able to learn secrets never before told outside a small circle of friends. And because it is the kind of love that does not overlook flaws or pretend they are not there, she has put it all down on paper. o

She played Callas' records constantly during the intensive four months while she was writing her first draft of the biography. "I always have music playing while I write," she says, "but not usually vocal music. For my first two books, I played Antal Dorati's recordings of the 104 Haydn symphonies over and over again, beginning with No. 1, going up to the end and then starting over again."

She even carried her research so far as to take singing lessons while she was writing the book -- "partly because I wanted to, anyway, but also to give me insights into her feelings and experience," she says. Then she took research beyond the call of duty by catching a cold and losing her voice. "I was doing a program for the BBC at that time," she recalls, "and I woke up one morning with no voice -- none at all, and I think I was secretly happy. I went to Dr. Norman Punt, who had treated her, and told him, 'I want you to do everything to me that you had ever done to her.' Well, I got injections directly into my throat; I was given what they call the 'Melba spray,' a mixture with a disgusting taste they spray into your throat. I was given special tablets, and an ointment that they apply right on the vocal cords with a very long Q-tip. My voice did come back -- at least enough to talk, though I would have hated to sing. And for the first time I really understood the vulnerability of the singer, and the way she would talk of her voice as something outside her, independent of her."

Stassinopoulos believes that her timing was fortunate in working on the biography: "She was recently dead -- and dead people are easier for a biographer because you know they won't come up with any new surprises. But she was still alive in the memories of many people, and I managed to get a lot of material that wasn't recorded or written down anywhere. It wasn't a moment too soon. Six people who were very important to this biography have already died since I began working on it -- her husband, Meneghini, just a few weeks ago."

At 30, Arianna Stassinopoulos looks a little like some of the more appealing photos of Callas herself; she has the kind of classic Greek beauty found in the ancient sculptures of her native land, and a mind just as extraordinary. An honor graduate of Cambridge University, where she studied economics, she was the first woman president of the university's famous debating society, the Cambridge Union. She is fluent in the four languages that were spoken by Callas -- Greek, English, Italian and French -- and before the Callas biography, she had written two books: "The Female Woman" and "The Other Revolution." Now, while she helps with preparations for the film based on her Callas biography, she is six months into her first novel: a fictional version of a murder story that happened in York, Pa., in 1928. The Callas biography has transformed her life.

"My first books were so theoretical and abstract" she says. "This one was completely different. For the first time, I had to come to terms with a real person, with deep emotions and intense pain."

Once, at the height of her success, Maria Callas said: "Only when I was singing did I feel loved."