Elisabeth Shue - 'You can enjoy the screams and the gore and the fun'

When Oscar-nominated actress Elisabeth Shue was first approached for the lead role in Alexandre Aja's explicit gore-fest Piranha 3D, she felt the film so outrageously absurd she simply couldn't resist. "I met with Alex and he convinced me to do it. At the end of our meeting he told me, 'you must go on an adventure'. How could I say 'no'?" asks the actress who, thus far, has built a career playing dark, emotionally complex characters, receiving an Oscar nomination for her role as a prostitute in 1995's Leaving Las Vegas with Nicolas Cage.

Despite her bravado, the demure Shue looks strangely out of place amid a cast full of B-listers in this Weinstein-marketed film, so shockingly violent and depraved it was banned from inclusion at Comic-Con's recent annual expo in San Diego, a closely-watched event attended by more than 150,000.

The location of Piranha 3D is a spring-break party on a lake where 40,000 students gather annually for a week of sun and drunken fun. But, this year, there's something more to worry about than hangovers and tan lines after a sudden underwater tremor sets free scores of prehistoric man-eating fish.

The film showcases the talents of Britain's own Kelly Brook, along with boatloads of actresses whose work is normally purveyed in adult DVD rental stores. Shue is one of the few "grown-ups" in the cast, together with Christopher Lloyd and Richard Dreyfus, reprising his role in Jaws.

"It was lovely to see Chris again," says Shue, 46, who won her first big break as a teenager in 1984's The Karate Kid, going on to star in Back to the Future II and III. "He's still like the mad professor from Back to the Future. I hadn't seen him for such a long time and he was the same, lovely, generous, very sweet man that he always was.

"It was funny to find ourselves both working on this film because I did have concerns, of course, and just the title was daunting. I don't think I would have ever taken the leap of faith if it wasn't for Alex because I felt like with him I was protected on an artistic level. I knew what kind of film it was going to be. I knew it was not going to be an art-house film on any level but I trusted his vision that it was going to be something that would be loud and colourful and fun and over-the-top and, yes, gory, but it would still have an emotional colour to it.

"And I knew that I had a tough job because I had to sort of provide the reality in the middle of it and knowing that the other tones would be very colourful and very different.

"My main concern was that people would at least follow the reality and not laugh at our story. And I haven't seen the whole film yet but everyone tells me that it actually works; that you can go with the broader moments and enjoy the gore and screaming and the fun of it and yet you still can follow the characters on an emotional level enough to care whether they live or die and actually be afraid for them. We'll see. That's definitely going to be a tenuous balance," says Shue, discussing the $24m (£15m) budget film which bears little similarity to Joe Dante's 1978 original Piranha other than gratuitous amounts of bare flesh.

Shue has been married for 16 years to director-producer Davis Guggenheim – who won Best Documentary Oscar for Al Gore's An Inconvenient Truth – and the couple have three children. And while Shue can hardly be described as your typical stay-at-home mum, she's honest enough to admit that she still likes to escape domesticity and get back on the film set.

"Just naturally it has been harder to find roles and I'm not really willing yet to do a series and work that hard. If anything, I feel like I sometimes need to work a little more, just to keep my independence and my own creativity alive, to stay a good mother rather than a mother who feels overwhelmed and suffocated. I always feel like there's this weird balance that a mother has to find where your individuality is alive and well, and then you're so much more present when you're with them.

"I don't work that often to be honest. It sort of comes down to really a film a year and then an odd thing here or there that only lasts a few days. If anything, I kind of pick up more of the slack. Davis has been working a lot in the last seven years. As far as choosing roles is concerned, a lot of times it's different based on where I am in my life and the different characters that I find interesting to explore, and probably one of the reasons I was interested in Piranha was that it gave me a chance to get physical.

"In my forties I've become obsessed with tennis and sports in general – maybe its somewhat of a regressed need to go back to my childhood," she says flexing a toned bicep.

"But it might also just be a place to find my individuality again and some place that's mine, because I do spend a lot of time with my kids, which I love. I'm very lucky that I have three extraordinary children that are worth every minute of the time I'm with them but I find that you also need to find outlets for yourself.

Over the years, I've been offered a lot of series that are tempting in that they shoot in LA and would provide some stability and obviously financial stability and all those things. But I have enough friends who've worked on series and I know what the time commitment is so, up to now, it just hasn't made sense. But I'm still open, there may be some great TV show that has a great ensemble cast and I wouldn't have to be the centre of focus and wouldn't have to work so much. And my youngest girl is only four so its hard to let go. Especially since she's my baby and I'm not planning to have any more so it is hard to imagine missing out on those moments," says Shue, who memorably starred in Woody Allen's Deconstructing Harry as well as starring opposite Robert De Niro in Hide and Seek, Kevin Bacon in Hollow Man and with Tom Cruise in Cocktail.

In Piranha 3D she plays Sheriff Julie Forester, whose job policing a sleepy town becomes a nightmare during the annual spring-break festivities. On this occasion, her job becomes personal when her own children are threatened by the deadly fish. "Thank the Lord I've never been called upon to save my own children from any real peril. But it's a pretty easy thing to act. Its an instinct that we all have and a fear that we all have. I believe that mothers can pick up cars if they need to get their child out from under one. I totally understand that need to protect your kids is so visceral that its pretty easy just to go to my imagination on that one," says this Harvard graduate who has no spring-break experience of her own.

"I never did that. These spring breaks that we hear about now seem like a completely different time. Maybe spring break became a much bigger deal once I'd already graduated. I remember hearing about it vaguely but the idea of it was not very appealing. I felt like the level of partying at a fraternity was pretty much as far as I needed to go."

Known for her research into her roles, she laughs when quizzed as to whether she did any similar work in playing a female sheriff. "This one happened fast and I didn't have as much time as usual and the nature of this film didn't really lend itself to too much analysis. I did struggle at first with the sense of authority – just that I've played so many roles where I've got to find my vulnerability, my sexuality and that dark complexity [about] what drives people, and I have to say on the first day of shooting, when I put on my boots and my badge and my gun and my polyester outfit and I walked on to the set, I felt very absurd!"

Entering show business early, Shue appeared in commercials for Burger King, De Beers diamonds and Hellman's mayonnaise, while still at school. However she's in no hurry to see her own children, Miles, 12, Stella, nine, and Agnes, four, follow in her footsteps.

"No, not really," muses the actress, whose own younger brother, Andrew Shue, followed her to Hollywood, where he became Melrose Place's resident TV heart-throb. "As far as my own children are concerned, I think it would be something I would have to edge them towards and I don't think I would ever do that. If they showed their own interest and they really tried to convince me that they loved acting and that they really wanted to try it, I would help them, for sure. But I would never put them into it," says Shue, who nevertheless admits to being impressed by her 14-year-old co-star Abigail Breslin, who plays her daughter in Shue's next film, Janie Jones.

"Abigail was just great. I'm a meth-addicted former groupie mother who can't take care of her anymore. Fifteen years earlier, her father and I had an affair and she doesn't even know she has a father, and he doesn't know he has a daughter, and I end up surrendering her to him. He's a down-and-out rock'n'roll star who has no choice but to take her in. I loved my part so much, although I didn't get to play it for more than a few days. Such a great role too – the darker, more complex and emotional the part is, the easier it is for me. But I don't take any of that stuff home with me at the end of the day."

'Piranha 3D' opens on 20 August