Daniel Day-Lewis is not fond of interviews. He hates talking about acting, his personal life, even the ways in which he chooses roles.

"I'm probably not the right person to speak about that," he says on more than one occasion as he fields questions about his new film There Will Be Blood.

Still, there is at least one subject which Day-Lewis warms to immediately. When asked about working with newcomer Dillon Freasier, who plays his son in the film, the actor tells a tale about the youngster's mother and how wary she was of the Hollywood folks interested in hiring her boy.

"Dillon's mom thought she'd go and rent a movie with that fella Daniel Day-Lewis," recalls the actor with a laugh.

"So she went and got Gangs of New York and was absolutely appalled. She thought she was releasing her dear child into the hands of this monster. So there was a flurry of phone calls and someone sent her The Age of Innocence, and apparently that did the trick."

You can't blame Mrs. Freasier for being nervous around Day-Lewis. Whether playing saints or scoundrels, pretty boys or prigs, the actor is utterly convincing. The ferocity he brings to oil tycoon Daniel Plainview in There Will Be Blood is astonishing. Already the recipient of a handful of critics' prizes and a Golden Globe nod, Day-Lewis is the favorite to take home his second Oscar in 2008.

For the 50-year-old Day-Lewis, all that intensity comes with a price. Even though he shies away from discussing it, he's a stickler for preparation. He spent eight weeks living with cerebral palsy sufferers before playing stricken author Christy Brown in My Left Foot (1989). He went three days without sleep before an interrogation scene in In The Name of the Father (1993). And he learned how to throw heavy knives before playing Bill the Butcher in Gangs of New York (2002).

The time and effort Day-Lewis puts into every role is why he's only made four films in the last decade. Needless to say, each new movie becomes something of an obsession for the actor. There Will Be Blood began with writer/director's Paul Thomas Anderson's discovery of Upton Sinclair's muckraking turn-of-the-century novel Oil!

Anderson decided to adapt the Sinclair book as a writing exercise. But soon he was hooked on the tale of a miner-turned-oil-prospector with a ferocious desire to succeed. Through a friend, Anderson heard that Day-Lewis had admired Punch-Drunk Love, so the filmmaker began imagining the actor in the leading role.

As written by Anderson, Plainview is a towering, larger-than-life figure who seems to embody the national thirst for adventure and instant wealth. As Lynn Hirshberg pointed out in a New York Times feature, the movie is "a story about what is right, and wrong, with America."

Some have called Plainview a monster but Day-Lewis is quite fond of the haunting and haunted character: "I never really saw him as this miserable prick," says the actor. "The challenge, I daresay, is the same as it always is, which is just to discover a life that isn't your own.

"Plainview, as he came to me in Paul's beautifully written script, was a man whose life I didn't understand at all. He was very mysterious to me and that unleashed a fatal curiosity, at which point I had no choice but to pursue the role."

As Plainview struggles to add to his vast wealth, he disposes of whatever—or whomever—stands in his way. His only human connection is his adopted son H.W. (Dillon Freasier), at least until H.W. loses his hearing in an accident and Plainview coldly rejects him. Despite all of that, Plainview remains strangely sympathetic, thanks largely to Day-Lewis' complex performance.

"I came to see him just as a fellow trying to make a living, really," says the actor.

Day-Lewis' determination to stay in character during the filming of the movie was, apparently, intimidating for Kel O'Neill, an actor hired to play Plainview's nemesis. At some point, O'Neill was let go and replaced by Paul Dano (Little Miss Sunshine).

"I was quite surprised when I read that [intimidation] comment," say Day-Lewis. "Whatever the problem was during that time with [O'Neill], I absolutely don't believe that it was because he was intimidated by me. I happen to believe that—and I hope I'm right."

The son of poet Cecil Day-Lewis and actress Jill Bacon, Daniel first came to prominence in 1985 when he popped up in two wildly different roles. In My Beautiful Laundrette, he was a gay street punk, and in Merchant Ivory's A Room with A View, he was the quintessential English snob.

He chose to play a prig, he told Hirschberg, in order to "understand what it is to be that man and thereby avoid the possibility of ever becoming him."

It wasn't until Day-Lewis played frontiersman Hawkeye in The Last of the Mohicans (1992) that he became a bonafide movie star. Roles in In the Name of the Father (1993) and The Boxer (1997) followed and, in 1993, he realized his lifelong ambition of working for Martin Scorsese on The Age of Innocence.

On the set of Arthur Miller's The Crucible (1996), he met the playwright's daughter Rebecca Miller. The two married and have two sons—Ronan, nine, and Cashel, five. (Day-Lewis also has a 12-year-old son Gabriel with actress Isabelle Adjani, with whom he had a brief affair).

While he'd never admit it himself, there are clearly parallels between Day-Lewis' obsession with acting and Plainview's willingness to muck about in the mire.

"Before rotary drilling came into common use, guys like Plainview would just scoop up this muck as it erupted naturally out of the earth," says an admiring Day-Lewis. "They scooped it up in sauce pans and buckets. In the beginning, it was just sheer blood and sweat. It's man at his most animalistic, digging through the dirt to find something of value."

After more than three decades as a performer, Day-Lewis struggles to explain how he's able to tunnel into a screenplay and come away with multi-layered characters rich in complexity and humanity.

"I'm really not the one to explain," he shrugs. "I suppose the illusion that [I'm] trying to create is that these things take care of themselves. It should [look effortless], as if there aren't any conscious decisions being made. I tried to allow Plainview's voice to be heard, for instance, and then once I hear it myself, I just try to make those sounds."