"I'm game for anything, " she says. "I love a challenge. It would be hard for me to sit around in a movie and just tell some guy how handsome he is and do absolutely nothing."

We're sitting in the shade of a eucalyptus tree at the edge of a manicured lawn that slopes from the villa where she and Rodriguez are staying. They're briefly in Locarno for a festival screening of Planet Terror, originally made as a double bill with Tarantino's Death Proof but now a separate movie because of poor box office takings.

McGowan is wearing a loose flimsy dress that ripples in the gentle breeze coming through the trees from the lake. "The sound of the wind in the trees is my favourite sound on earth, " she says. "It just makes me want to take a nap in the grass under the trees."

Rodriguez is over by the pool taking a call on his cell-phone, his face shielded from the sun by a wide-brimmed black Texan cowboy hat. "I started wearing it because it's called The Troublemaker and that's pretty much what I am, " he once told me.

He's so smitten by McGowan that last year he divorced Elizabeth Avellan, his wife of 16 years and the mother of his five children . . . Rocket, Racer Max, Rebel, Rogue and Rhiannon. Their names all bear his RR initials and they all featured in his hit Spy Kids trilogy.

Apparently it was an amicable separation and Avellan, who encouraged him to enter his schoolboy movies for competitions when she met him at the University of Texas, has continued as producer of Planet Terror and vicepresident of his company Troublemaker Pictures.

Rodriguez and McGowan were pictured holding hands at Cannes Film Festival earlier this year. Last month they announced their engagement. "We first met a couple of years ago and we got along so well, " he told me.

"This girl, she's funny, she's acerbic, she's whiplash sharp, so quick-witted, so beautiful. I was like, where have you been?

You used to be in movies, you were Neve Campbell's best friend in Scream, what happened to you? 'Oh, ' she said, 'I've been stuck in a TV show, Charmed, for five years.' So that's it, I said, I don't watch TV. You should be starring in movies. In fact, that's my new mission."

Rodriguez hasn't quite accomplished that yet in Planet Terror, but comes close.

"She told me, 'I like all your scripts but that's because of the guys. How come the guy can't be a girl? If you write something, give me the guy part.'" It made him realise that Planet Terror, his spoof on 1970s zombie gore-fests, would be more interesting if a girl saved the world.

"I write guy parts because I'm a guy, " he says. "I don't know what it's like to be a woman. I can pretend but it's going to be fake. So for a while I just listened to Rose and observed her. And a lot of the lines that she says in Planet Terror were stuff that she had said. When she read the script, she said, that's me! I know, I said, it's kind of like a version of you, but with a machine gun."

The go-go dancer character she plays resonates because it's really based on somebody's personality. But according to Rodriquez, "It still doesn't capture Rose. If you see her in the movie and see her in life, it still can't really compare to what she has."

Perhaps his forthcoming remake of Barbarella, a reprise of the cult Roger Vadim sci-fi extravaganza in which McGowan will take on the sexually outre role originated by Jane Fonda, might.

"Maybe, baby, " laughs McGowan.

"I don't know. I still want to do Jane Eyre. I still want to do Clara Bow. There are so many things I want to do. I really do feel there are some things you do that are kind of like candy, and I love candy.

But I like steak also. I know what I'm capable of doing and I know I haven't gotten to do it yet."

She pushes a wisp of red hair from her face. "Red is my natural colour, " she says. "I suppose it's the Irish in me. But since I'm so pale I can do any colour. I made myself darker for Planet Terror. I wanted to look more Italian, a little more exotic. Because I was wearing very little clothing, somehow having all that body make-up on me made me feel less naked."

Being in an Italian-speaking part of Switzerland has resonances for her. She was born in Florence in 1973 and raised in a commune run by the Children of God hippy cult, of which her Irish artist father, Daniel McGowan, and mother Terri were members.

"The kids were kept really separate so I don't have any memories of my parents until they were out of there and back in the States and by then they were divorced and I was 10. I spoke Italian before I spoke English. Now I only speak Italian in my sleep. I remember having German nannies and things like that. I guess looking back it was pretty weird not having any contact with your parents. But I don't know any different. Whatever you grow up with is what is. I could never imagine my mom making cookies like other moms."

She officially emancipated herself from her parents when she was 15. "I went to about 10 different schools. I'd go to the library and hide and read because I knew I was going to move again, so why make friends. I was five-foot tall and scrawny but I was working in the market in Seattle moving crates when I was 13. I didn't like being told I couldn't do something.

"Maybe my life would have been easier if I'd grown up 'normal', but I don't know what 'normal' is. I've always felt pretty old. I never had young friends when I was little. I was only friends with adults. In a lot of the schools I went to the kids who looked like the perfect blonde blue-eyed goodies were the ones who were the drunks, the drug addicts, the thieves. And the kids they thought dressed weird and persecuted . . . including myself . . .

weren't."

Up to now, home has been in Los Feliz in LA. "I'm just up the street from Little Armenia. Most people there are trying to escape from something else. What I love is you can really just reinvent yourself."

Home for Rodriguez is Austin, Texas, where he still edits all his movies. "I work a lot at home. I cook my own meals. Cooking is the same as filmmaking. It's art that you get to eat. That's why I'm my own editor. I don't understand how you can call yourself a chef if all you do is buy the ingredients."

Although Rodriguez wrote Planet Terror for McGowan, she still had to audition. "He doesn't cut you any slack. I had to go around with my leg in a heavy cast so I'd have the right motion to enable the effects artists to digitally remove my leg. Each day I just tried not to fall. It's like wearing very high heels all day. He insisted that I had to run as fast as everybody else, up and down hills.

My acting triumph was not to fall down."

Rodriguez and Tarantino have been friends since they met at a film festival in 1991. He'd just scored a phenomenal hit with his $7,000 debut action flick El Mariachi, which he wrote, produced, directed, scored and shot in his back yard using members of his own family . . . he was only 24 . . . while Tarantino was making his breakthrough with Reservoir Dogs.

"I went back to my office at Columbia to do Desperado and it turned out Quentin was writing Pulp Fiction for TriStar Pictures so he had an office a couple of doors down from me. For the next year we'd go out to lunch together and read our stuff to each other.

And then he was in Desperado and we ended up becoming collaborators."

Just as Tarantino delights in rediscovering neglected or forgotten stars, Rodriguez has made a habit of creating them.

He's now doing for McGowan what he did for Antonio Banderas and Salma Hayak in Desperado.

"It's cheaper than hiring a star, " he says. "I gave George Clooney his first movie just because I saw him on a talk show and he didn't like the guy who was interviewing him. I called him to meet with me in my house. He drove up on a Harley. I thought this is the guy. No one else was offering him roles after ER. I surprised everyone by giving him the lead in From Dusk To Dawn."

McGowan regrets she's never been to Ireland. "The funny thing is my mom goes all the time, she works for Microsoft, " she says. "If I go there, can I have someone call you? I don't drink beer or ale, but we could have a really nice breakfast together."