On the contrary, I was utterly convinced it was silly. A friend, Joanna Wexler, had told me I had to write about Oxford and I'd done a little research, but I certainly wasn't a convert. Originally I thought I'd write a comedy about silly people who believe Shakespeare isn't Shakespeare, and why they believe it, and I'd put a forgery in.

And you were going to write it for Otto Penzler?

He asked me for a 60-page chapbook, and I decided to do the Shakespeare authorship story for him. He got it, called me up and said, "It's marvelous, marvelous…but, um, did I tell you the name of the series," and it was something like Guns, Gore, and Girls.

Was Posy part of it then?

Posy was there from the beginning. As I recall, the 60-page version begins "Posy believes in Shakespeare and Posy," something like that. From the beginning she was this tremendous egotist who was still young and vulnerable and, of course, lusciously attractive.

And has good clothes.

Posy went out shopping with two women writer friends of mine, Shariann Lewitt and Dora Goss. We found outrageous pink and green and fluorescent orange clothes, and tiny black miniskirts, and Dora decided she had to have a necklace of enormous real pearls.

That pearl necklace works nicely with Elizabeth's.

It was fun doodling with parallels between the Elizabethan world and modern London. Posy's necklace; Joe going up in the London Eye and seeing the medieval walls of the City of London; Southampton in jeans making an entrance at the Diesel Café near Posy's apartment. My favorite is Joe discovering where the Theatre was, and looking back down the road toward Fisher's Folly, and four hundred years melt away like snow under his workboots.

Did living in England help you to write the book?

I'd lived in London, but I'd never really seen the City, so I had to do a lot of onsite research there. And of course I had to research the whole Elizabethan piece.

To what extent do you use your background as an English scholar?

As little as possible, really. When I was in grad school, everything was hugely theoretical--my thesis advisor invented the idea that the writer's biography didn't matter. The things that worked for me in grad school were reading everything, reading the unimportant books--that was considered a very dull thing to do.

I had the great luck to take Shakespeare from Robert Lowell. He would sit in front of the class and read the play aloud, very slowly, in a rumbling deep voice with that New England accent, and every once in a while he'd stop and say "Hamlet was mad," or "Falstaff was mad," or "That's a good line." He taught me to hear the music. He told me my final paper for the class made him cry, which is the best praise I ever got in grad school.

I suppose, come to think of it, Joe's way of speaking comes from Robert Lowell.

Joe's an odd choice for the main character of an academic mystery. How did you come up with him, and why did you decide to make him the man he is?

Joe was the hardest character to write. When you're writing a first-person story, the story has to matter to the main character more than it could ever matter to anyone else in the world. What goes wrong has to be utterly wrong, utterly destructive, the end of the world. Who would have complete faith that Shakespeare is Shakespeare, and who would be completely devastated if he weren't?

So Joe Roper is a man like Shakespeare, with even fewer advantages than Shakespeare. He comes from a nearly dead town in Vermont; his father runs a hardware store. When he was nine years old he started reading Shakespeare by accident, and destiny's finger pointed at him and the lightning struck, and he fell in love with Shakespeare and wanted to know who this man was. He's bootstrapped his way up through the University of Vermont, he's working his way through graduate school at Northeastern by installing windows, and somehow, somehow, he wants to get good enough to write Shakespeare's biography. He's been given the chance of cataloging a collection of Elizabethan materials, and in it he finds a letter--supposedly from Shakespeare, saying Shakespeare didn't write the plays.

And is he devastated?

Well, no; at the beginning, he's absolutely sure the letter's a forgery. So he intends to act like a literary detective and prove it's wrong, because he's Shakespeare's man.

That letter's fictional, but most of what they find is historical evidence. Can you talk about how that happened? Did you find all this evidence yourself?

A lot of people have written about the authorship controversy and I stole from them. But I did find a couple of things, and one big thing, the poem.

In the book, Katherine Darnell says that "If it is important to know who wrote Shakespeare's plays, if it is important to find lost plays or poetry by Oxford, I believe…that by some miracle someone will find it." How did you find it? Did you deduce that the poem had to be where it was, or was it a miracle?

You have no idea. What Joe does in the book was more or less what I did. He looks at a minor playwright who might have worked with Shakespeare, Anthony Munday. He starts reading Munday, and he comes across a volume from the Elizabethan era with three small books of poetry in it. He reads two of them, and they're awful, and he's tempted to give the volume back to the librarian without reading the third; but he grits his teeth and keeps reading, and in the third book, there's a poem that's much too good to be Munday.

I gave the book back.

I gave the book back, it was past lunchtime, I was tired, and then thought, "Naah, you know, I'll never find a copy of this book anywhere else, I'd better take a look at it." And, goodness, it wasn't bad at all. I liked it so much I asked the British Library if I could get a Xerox of it, and, bless their hearts, they Xeroxed this Elizabethan book for me.

I didn't get to read it until I was on the plane going back to America. We were trying to take off from Heathrow, into the middle of an enormous storm, winds something like 90mph, driving rain. The plane was skittering down the runway like spit on a griddle, and I was reading the poem to take my mind off things, and I began to notice all those amazing words and how good the poetry was and I put my hands together and prayed, "Don't let me die, don't let me die, I have to tell someone about this."

Is the poem Shakespeare's?

That would be hard to say. Who is Shakespeare, over ten years before the earliest datable piece of Shakespeare we have? How would he write before he'd read Sidney and Spenser and Marlowe? But I would bet significant money it's Oxford's.

But what you're really saying is that you have the smoking gun, a big Shakespearean poem that was written by the Earl of Oxford.

I'm very carefully not saying that. First, Joe's passion is my passion; I adore Shakespeare. I think if one's going to say something so radical about him, one should prove it again and again and again, and one should keep an open mind until then. The more one prepares one's mind to see every argument, the better one sees.

And, second, it scares me. I found something like that? Who am I?

But it's Oxford's. And it's more like Shakespeare's work, in hard-to-duplicate ways, than anything else I've read.

With all this new information, why did you write a novel, not a Shakespeare biography?

As if I could. But the real answer is that the Shakespeare story isn't only about Shakespeare's life; it's a much more complex story that includes Shakespeare the man, Shakespeare the idol, Shakespeare the genius, our readings of Shakespeare over the past four hundred years. As Marjorie Garber has said, she doesn't want to know too much about Shakespeare's mere life because she wants to leave him sufficiently blank to hold the rest of the story.

To tell a huge, complex story like Shakespeare's, you need a big group of characters, each holding on passionately to his or her own Shakespeare and denying all the rest. You want them dissing each other's ideas and betraying each other and stealing manuscripts and doing all the stupid things that keep us shaking our heads and laughing.

The most magical moment of a story is when one character says something, and it's true, and another character criticizes it, and that's true too. Novels leave room for many layers of truth.

How did you choose the names you did?

In the first novella version of the story, I thought it would be cute if everyone had the sort of allegorical names that characters had in Tudor-Stuart plays, "gold" and "gossamer" and so on. If Posy ends up marrying Joe, she'll be Margaret Roper, who was St. Thomas More's beloved daughter. Stupid author tricks, but the names seemed to suit them, so I kept them.

Does the meaning of that ladder-type thing on the front of the book become clear by the end of the book? Does it have a meaning?

I have no idea what it means, but anything that beautiful must have a meaning.

Was it easier to write this book than the historical mysteries? How long did it take you?

This was actually easier to write because I had the scaffolding of Oxford's life. But when I found the poem, I realized it had to be part of the book, and that meant a lot of rewriting.

Will the characters continue in another book?

No, I think this is a one-off. But there could be a book with an Elizabethan setting...

Who do you see playing the lead roles in the movie?

Posy wants Cate Blanchett to play her, but Posy's fantasizing herself tall and blond and gorgeous. I wrote Joe's role thinking of Matt Damon, but I'm probably fantasizing too. It would be marvelous if he did it. He would be perfect.

What's next? Any more of your previous series?

I'm working on a book set in New York about survivors of a tragedy--but the time is 1912 and the tragedy is the sinking of the Titanic. It's the fourth of the increasingly inaccurately named Vanished Child trilogy. The working title is A Woman's Voice.