Julianne Moore on Chloe

Julianne Moore is a true rarity. It's not just that her hair flames like no other star since Katharine Hepburn. Or that alone of her generation she seems impervious to middle age's indignities — she is 50 this year. There's something else.

Having worked with dinosaurs in The Lost World and a cannibal in Hannibal, she is mainstream enough to be considered a genuine leading lady. But much of her most eye-catching work, often written for her by indie directors like Todd Haynes and Paul Thomas Anderson, is fiercely extreme in spirit. Pornography, incest, erotica — hers would be bargepole roles for most actresses.

But Moore isn't most actresses. She is the closest the English-speaking world can boast to a French actress. Hence Chloe. Adapted from Anne Fontaine's Parisian three-hander Nathalie (2003), Moore plays a Toronto gynaecologist who, suspecting her husband (Liam Neeson) of infidelity, commissions a prostitute to seduce him and report back: this is Catherine's creative way of looking for clues that might explain why the spark has exited the bedroom.

Intriguing co-dependency

It's a thoroughly French scenario, given a cool Canadian twist by director Atom Egoyan. It turns out that Moore didn't know about Nathalie. "They told me it's based on a French film," she says, "and I didn't watch it because I'm incredibly suggestible and didn't want to be in a place where I felt I was ‘doing' Fanny Ardant. Chloe takes the idea of the French film," she adds, "and goes that much farther."

Like much of Moore's best work, this is an understatement. In both films, gynaecologist and prostitute grow intriguingly co-dependent. Moore and the comely Amanda Seyfried — 24 years her junior — even find themselves acting out a male fantasist's scenario. What on earth did Moore think when she read the script? She emits a startled laugh. "It made me nervous," she admits.

"It's tricky stuff to do. Had this come to me with somebody other than Atom attached it would have really given me pause. Honestly, unless you're in Catherine's decisions every step of the way, then yeah, it can be prurient or salacious. Obviously there's something inherently dangerous about doing a scene like that, but it was all very deliberately staged, we watched playback, we were able to adjust things."

According to Moore, the film needs the sexual encounter — and as a preamble to Egoyan's revamped ending, perhaps it does. The interesting thing, she says, "was that in the scene I won't look at her. The line that Catherine is drawing is about sheer fantasy, it's about how do I get back to him, so she says, ‘Show me, how does he do it?'"

It's another erotically charged role in which Moore goes the extra mile. How does she do it? "It's not like I ever intend to!" she protests. "I never do. I think it's happened a lot of times because I'm involved in things that are love stories. There are times when I feel it's absolutely not necessary at all."

Her most exposing role was in Far From Heaven (2002), Haynes' pastiche of the '50s weepie in which Moore matchlessly embodied a fey housewifely brittleness (she used some of the same brushstrokes in The Hours). Here the nakedness was all emotional: she was entirely clothed. "And pregnant," she volunteers. Did the raging hormones make a difference? "I don't think so. It was my second trimester, when generally you feel OK." Her son and daughter are now 12 and seven.

The family lives in Manhattan where, in 2007, Moore was persuaded to make a prodigal return to the stage — before she was scooped up by cinema at 30, all her work had been in theatre and cheesy television. The play was The Vertical Hour, David Hare's thinkpiece on the morality of war-mongering in the Gulf. But for her it didn't quite work. "It's very difficult to do when you have kids because the hours are fairly extreme. I did find it particularly difficult to do Broadway. It was not my favourite way to perform."

Now, Moore yearns to explore other areas of her palette. She was hilariously slow-witted in Robert Altman's Cookie's Fortune (1999) and regrets the lack of opportunity to make audiences laugh. In fact, she recently guested in 30 Rock. "You want to have variety as an actor. If you spend your career doing one thing solidly, people get burned out."

No evidence yet.