The girl who plays the girl with the dragon tattoo

As she prepared for her third film outing as the ferocious computer hacker-turned-investigator Lisbeth Salander, actress Noomi Rapace sat in front of a mirror, holding an electric razor to her skull.

Her six-year-son sat quietly watching her. He may not have understood how a role like this, playing the heroine of a series of bestselling crime novels, could make a young actress's career. He only knew that his mom had already pierced her nose and her eyebrow, dyed her hair black, and spent an awful lot of time kickboxing at the gym. Now she was about to shave her head, leaving only a stiff Mohawk.

"Why do you want to do that, mommy?" he finally asked. "You look like a teenaged boy!"

Rapace snorts with laughter as she tells this story, and she's got a pretty big laugh for a tiny person. A tiny person in some seriously beautiful, platform satin shoes, which Lisbeth Salander would never contemplate wearing, though she might beat a thug to death with them. Only if he deserved it, of course.

Rapace, with her perfect manicure and glossy chestnut hair, looks so little like the eponymous hero of The Girl with the Dragon Tattoo that I at first ignored her when she came to sit next to me in the lobby of London's Soho Hotel. I'm in good, if dim-witted, company; Niels Arden Oplev, the director of Girl and its two Swedish-language sequels, recently made the same mistake. ( The Girl with the Dragon Tattoo is released in Canada on Friday.)

"He walked right by me in a hotel and didn't recognize me," says Rapace, 30, who grew up in Sweden and Iceland and speaks excellent idiomatic English. The fact that he ignored her is perhaps not so odd, because she got used to being overlooked in her pursuit of the Salander role. Apparently the only person in Sweden who thought that Rapace was the right person to play the ferocious, anti-establishment heroine of Stieg Larsson's Millennium trilogy was Rapace herself.

"I was actually very upset when I read that they were going to make [the first novel]into a film of it because I was so sure they wouldn't consider me," she says. The producers at first thought she was "too girly, too feminine. … but I'm an actress. I can do fat and blond or skinny and black-haired."

Once she'd got the part, she embarked on a strict regime of diet and exercise - Larsson writes that Salander is "a pale, anorexic young woman" - as well as martial arts and motorcycle riding, the better to whup some misogynist butt. (In Sweden, the title of the first novel and film translates to Men Who Hate Women, and the film contains a very graphic scene of Lisbeth's revenge on a man who abused her.)

If you're not one of the more than 20 million people who have read Larsson's books, Salander is the damaged but resourceful computer genius who hooks up with crusading journalist Mikael Blomkvist to solve a series of crimes. "I wanted to humanize her, because I think she's a bit cartoonish sometimes in the books," says Rapace. "She can do things that are not really credible or realistic. I wanted to turn her into a real person."

The Millennium trilogy - named after the investigative magazine that Blomkvist runs - are the only Salander tales that the world will have. Larsson, a graphic designer and journalist who investigated Sweden's far right, died in 2004 after completing the three novels. He was 50 years old, and because he made enemies on the far right, there are conspiracy theories surrounding his death. A fourth novel is said to exist, at least in part, on his computer, but it's the subject of a fierce contest between Larsson's longtime partner, Eva Gabrielsson, and his father and brother, who inherited his estate. Because Larsson and Gabrielsson weren't married, and he died without a will, she doesn't have any claim to his books.

Six years after his death, Larsson is a mini-industry, having stained the impeccable reputation of Sweden as an egalitarian, bleached-pine nirvana, although Henning Mankell's Wallander mysteries helped with that. There are very popular Stieg Larsson walking tours of Stockholm, which trace the steps of Blomkvist and his tattooed sidekick.

Most readers assume that Blomkvist, the noble reporter who's caviar to women, is the authorial stand-in, but Rapace thinks the chain-smoking, publicity-avoiding Larsson was closer to another of his characters. "I think he's more similar to Lisbeth," she says. "He was shy, he was a workaholic. He was fighting his own personal war against power abuse."

When Rapace finished filming the third instalment, The Girl Who Kicked the Hornets' Nest, she carefully took out the facial piercings she'd had done and grew out her hair. "I looked like shit after," she sighs. She was about to go on stage to play Medea, another ferocious female character but perhaps not one as fond of nose rings.

Now after three films and a couple of awards for her performance, Rapace is happy to leave the girl with the dragon tattoo behind. She's heard that there is a U.S. remake in the works, and though she can't imagine a Hollywood version of Salander - "she's so dark and aggressive, what are they going to do?" - she wishes them well. She just doesn't want to be involved.

"They haven't asked, but even if they did ask me I wouldn't," she says. "It's good to let things go." Her son would probably agree.