Kathleen McGowan has received a seven-figure advance for her novel, "The Expected One," said the Sunday Times of London.
The book will be published in New York on Tuesday. It has earned $2 million from the sale of foreign rights and will appear in Britain on Aug. 7.
McGowan, 43, said she had submitted her proposal to publishers in 1997, six years before author Dan Brown published "The Da Vinci Code" -- which features a plot line involving descendants of Jesus and Mary Magdalene.
McGowan self-published her book last year after she was "laughed out of New York City," she said. It sold 2,500 copies but was snapped up by Touchstone Books, an imprint of Simon & Schuster.
"The Expected One" tells the story of Maureen Paschal, a journalist searching in the Pyrenees for scrolls supposedly written in the first century by Magdalene.
When asked to produce ancient family documents that she claims to have uncovered in France, she said she had been "asked not to talk about what I've seen."