Patricia Arquette: The not-so-dippy hippie

Hours before we meet, I watch Patricia Arquette club Tony Soprano to death in her underwear. But, even with a dead hitman in her lap, Arquette looks angelic. It's easy to forget how shocking True Romance was back in 1993. Starring Arquette, Christian Slater and James Gandolfini, Tony Scott's film starts off as an odd-couple romance and ends as violent farce. It also gave Arquette the role of a lifetime.

In the mid-1990s, Arquette was indie cinema's favourite blonde. Working with auteurs such as David Lynch, Tim Burton, Sean Penn and David O Russell, she brought a quirky intelligence and vulnerability to the screen, reminiscent of early Monroe. When she married Nic Cage in 1995, it was hailed as the merger of two acting dynasties.

Men lusted after Arquette but women loved her, too. She has never conformed to the size-zero Hollywood stereotype: petite (5ft 1in) and curvy, she never had her teeth fixed or worked out for a nude scene. As for her role in Michel Gondry's Human Nature, it's hard not to love a woman battling copious body hair.

Arquette has always made brave choices. But there's no denying her film career went quiet. Now she's back with a bang in the hit TV crime series, Medium (the role won her a 2005 Best Actress Emmy), inspired by the real-life psychic Allison DuBois. The show is the brainchild of Glenn Gordon Caron (who created Moonlighting) and is produced by Frasier's Kelsey Grammar.

"There's just better writing for women my age on TV," Arquette says. She has no time for people who are snobbish about TV. "My grandparents were in vaudeville, which was like a cheap form of entertainment. I look at it like that with television."

We meet at NBC's London office. Arquette looks amazing in a Jessica Rabbit-style dress. "Oh, a stylist picked this out," she laughs. "I'm just off honeymoon, so the last thing I needed was a clutch of business clothes." In June she married actor Thomas Jane, the father of her three-year-old daughter Harlow, at Venice's Palazzo Contarini.

Her personal life hasn't always been so idyllic, however. Arquette has spent most of her life as a single mother (at 19 she had a son Enzo, now 17, from a relationship with musician Paul Rossi). Her marriage to Cage wasn't easy. They met in a Los Angeles deli, where Cage proposed on the spot. She accepted on the condition that he fulfil certain conditions, including obtaining the autograph of JD Salinger and tracking down a black orchid. Nine months after their wedding, they separated, but continued appearing as a couple until filing for divorce in 2001.

Today she and Jane live in sleek, modern beach house in Miami. How does she balance having a teenager and a three-year-old? "I'd always been very protective, but he was just starting to need a little more freedom. So he was relieved I had someone who was a baby. I almost see myself as having two lives: I had Enzo and we grew up together. I'm a woman now, and I'm in a partnership. I just feel much more mellow."

In the States, Medium gets higher viewing figures than CSI. Arquette is terrific as the ballsy Allison, and has great chemistry with Jake Weber, who plays her husband. "She's not some supermodel, but he's hot for her and she's hot for him. It's a committed sexual marriage, which you rarely see in film or TV."

For all her flower-child reputation, she loves playing a working mother of three. "When I first got the show I'd just had my daughter and gained about 20lb. One of the producers said, 'Honey, you've gotta lose some weight!' There's still this Dynasty-esque thing happening on network TV. But when I spoke to Glenn, he said, 'What? No, you don't have to lose any weight. You look great.'"

Her Medium wardrobe is deliberately unglamorous. "I had a feeling that women wanted to see something different: different types of body shapes, different faces." It's worked - 60 per cent of viewers are female. With its storyline of a crime-busting housewife, it may not sound radical, but Medium is filmed in a very experimental way. Much of the action takes place in Allison's mind - with surreal dream sequences, jump-cutting and even a 3D episode. "Before I started the project, I thought I'd love to be able to read minds," says Arquette, who spent time interviewing the real-life Allison. "But it's a lot to carry. There are times when Allison sees the crime through the perpetrator's eyes."

Medium leaves her little time for film making. Does she despair of the industry now? "Twenty years ago, directors were allowed to make their movies. They could cast whoever they felt was right for the character. But now people come in from all these different businesses, they want to make glamorous movies in Hollywood, and they don't have any sense of film history. Business people think, 'Lord of the Rings made a lot of money so we want to make almost Lord of the Rings but call it... Master of the Necklace.'"

Arquette does understand film history. Her grandfather, Cliff, was an actor and comedian. Her father, Lewis Arquette, was JD Pickett in The Waltons. Her sister, Rosanna inspired the Toto hit song. Her brothers, Richmond, Alexis and David (married to Courtney Cox), are all actors. In fact, Alexis, a drag performer, recently had a sex change.

At times the clan can seem pleasantly bonkers. Does she find it odd we're so fascinated? "Well, for years it was like: 'Oh, the quirky family!' For a long time we were 'We're not a quirky family, we're normal.' But then with maturity, you get like, 'Oh, I don't care, if it's fun for you to play silly games, go ahead.' As public as we are, we're also very private. When we're all together we don't talk about work much. Dave just directed a film with Richmond, Courtney and Thomas. It's really a funny, smart horror movie-slash-comedy. But come round our house and we're more likely to talk about babies."

Over the years, she's worked with some fascinating directors. "I had a very paternal-maternal relationship with all of them. Tim Burton has his own visual genius and a beautiful sense of gentleness for the character. Diane Keaton would just touch me on my back before a crying scene and I'd feel such a rapport, we were so symbiotically connected. Sean would whisper little secrets that your character would know before the scene. Each of these directors gave me a golden tool which I just put in my tool chest."

Growing up in the Sixties she went on peace marches with her mother Mardi, a poet and political activist. Today Arquette campaigns for civil rights, breast cancer awareness (her mother died of the disease in 1997) and environmental justice.

There aren't many Hollywood actresses who would talk to you about the Middle East. But Arquette's mother was Jewish (the daughter of a Holocaust survivor from Poland) while her father, a Christian of French ancestry, later converted to Islam. After September 11 she got involved in a project helping Arab-Americans who had been victims of hate crimes. "'I was trying to say, 'Wait a second, I grew up in a family with a Jewish mother and an Islamic father who did Ramadan and there was never any religious conflict in our home.' I know so many Islamic people who aren't militant and I just saw this media machine moving forward, fear closing people down, and basically I was really worried about what's happening in the world... and now, of course, this division is getting worse. People hunkering down in this most exclusive, divisive way."

Arquette is an unrepentant child of the Sixties. "Even coming here to London to do a junket, they asked me to sign me this six-page thing saying, 'You will not get arrested other than an auto infringement', and you know," she beams, "my little problem with authority meant I just did not want to sign it. It's like everything - taxes, marriage, death - we're just drowning in bureaucracy."

'Medium' is on the Sci-Fi channel every Monday at 9pm