Keira Knightley Keira Knightley

Before there was Harry Potter and The Lord of the Rings, there was Pride & Prejudice and the legions of loyal readers ready to be up in arms over any damage done to their beloved Jane Austen novel for big or small screens. And no one's more aware of this potential danger than Keira Knightley, a loyal fan of the author since childhood and the star of the latest feature adaptation (in select theaters today).

"It's a difficult thing, when you try to make a film of a book that you really love, because you only ever have about two hours to tell the story, and it's never going to be enough, you know," Knightley tells TVGuide.com. "We don't say the most famous line in the entire book ["It is a truth universally acknowledged that a single man in possession of a good fortune must be in want of a wife"], which I think is kind of quite good, actually, because you expect that one."

For those of you not overly familiar with the story, here's a quick P&P recap: Lizzie (played by Knightley) is the second of five daughters of a reasonably well-off small-town landowner, whose estate will unfortunately be inherited by the nearest male relative, so they all have to get married to survive. While mild, eldest sister Jane catches the eye of a sweet rich guy, sharp-tongued Lizzie has a love-hate relationship with his snooty, richer friend. Then, of course, their pride, prejudices and meddling relatives get in the way of their happiness.

"I've been obsessed by the book since I was about 7, when I had all the Austen [books] on tape," says the actress. "When I was offered the role, I was terrified of doing it, because I'd been really obsessed with the BBC [miniseries]. I thought, 'I'm just going to do an absolute copy of Jennifer Ehle's performance and that would be awful. I mean, she was fantastic, but it would be awful if I tried to copy her."

Knightley's mother soon soothed such fears, advising her daughter to read the book one more time. "She said, 'If you read the book, you'll see yourself as Elizabeth Bennet, and therefore you won't be able to do a copy of anyone else's performance,'" Knightley recalls. "I think that's one of the reasons why the [book's popularity] has lasted as long as it has, because if you're a woman and you love it, you read it and think, 'Yeah, yeah, that's me!'"

So with extensive lessons in etiquette, history and early-19th-century dancing, not to mention authentically dirty period costumes, Knightley quickly immersed herself into the character. Then another problem presented itself: While still filming Pride & Prejudice, the in-demand ingenue had to begin preparing for her role as real-life model-turned-bounty-hunter in Domino.

"Domino is a crazy script anyway, so it's difficult at the best of times to get your head into that — but even more difficult when your head is so far into Pride & Prejudice and Elizabeth Bennet," she says. To prepare herself for the transition, she escaped to a London salon on a weekend break to chop off her lovely locks. "I needed to look in the mirror and not see Elizabeth Bennet.... so I had to cut it off.

"I think it was incredibly stupid — and putting ridiculous pressure on myself — to do the films that close together," she adds in retrospect. And filming back-to-back sequels to 2003's Pirates of the Caribbean: The Curse of the Black Pearl hasn't been much easier. "I've been working too much. Last weekend I worked 32 hours straight; the weekend before I worked 32 hours straight. I will have a day off in approximately, oh, a month?"

When Pirates of the Caribbean: Dead Man's Chest wraps and that day off comes, Knightley promises not to spend it preparing herself for yet another character. "I'm going to go home to London and sit in my flat and not move."