The driver who picks me up from LAX is called Curry Grant. Truly. He is 80, from Louisiana, and full of good stories.

He asks me whether I'm an actress. I tell him I'm here to interview someone. He asks me who.

"Daniel Day-Lewis," I say.

"Nicest guy I've ever had in this car. Picked him from the Hotel Bel-Air 10 years ago, took him to the airport; the nicest guy in the world. Him and Mel Gibson."

Curry Grant's accolades increase my anticipation, because from what I have imagined so far, Day-Lewis will be engaging and fascinating, if not a bit bleak and narcissistic, like a Russian romantic. Originally, I was sure the interview would take place somewhere remote near Ireland's Wicklow Mountains (because that's where he lives a lot of the time), in a pub that has flouted the smoking ban due to its clever location and wily bearded landlord. Day-Lewis and I would smoke and drink Guinness, and, as a lovely peat fire crackled before us, we might eat some fresh Dublin Bay prawns. My fantasy peat smoke dissolves into smog when I find out that the interview will take place in Los Angeles.

Over the course of the next few weeks, as I stay up late to read a thick file of clips and talk to a few people, I begin to despair. I have no grasp of who Daniel Day-Lewis is. And the little I do know of the myth infuses me with worry. Everyone seems to have an opinion: He's difficult, he's beady, he's spiky, he's mad. Don't ask this question; don't ask that.

I will not be seeing his upcoming film, There Will Be Blood, until the day before I meet him, so I plunge into his early films to see if I can get a sense of him. On the screen, I meet Christy Brown (the wheelchair-bound writer and artist of My Left Foot, which earned Day-Lewis an Oscar for Best Actor in 1990); Hawkeye (The Last of the Mohicans); Newland Archer (Martin Scorsese's The Age of Innocence); Gerry Conlon (In the Name of the Father, and another Oscar nomination); Bill the Butcher (Scorsese's Gangs of New York, Oscar nomination No. 3); Jack Slavin (The Ballad of Jack and Rose, directed by his wife, Rebecca Miller, with whom he fell in love after working on her father Arthur Miller's The Crucible in 1996). But nowhere to be found is Day-Lewis himself, not a trace of him, even in his physical self. His ability to inhabit each role down to its bones is the stuff of legend, and in my jumpy anxiety, I decide he might be some sort of a sorcerer.

"One of the advantages that Daniel has," says Paul Thomas Anderson, the director of There Will Be Blood, when we speak on the phone, "is you don't see him everywhere, so you don't really know who he is or suffer through having to see him every day in the newspaper. So he already has that advantage to be somebody else. Beyond that—it's still magic to me."