It’s difficult to think of a part of any other major city quite like it. To the south is the gridwork of greater Los Angeles, stretching from the desert in the east to the ocean in the west, and fading away in the smog to the south towards Orange County and the unforgettably named John Wayne International Airport. To the north is another grid: the huge suburban sprawl of the San Fernando Valley, as unlike a valley as anything you are ever likely to see, where ranches and citrus groves have been swallowed up into the endless affluence of homes and malls. In between lies the Canyon.

There are no grids here, just winding roads and idiosyncratic, architect-designed homes perching on hillsides and outcrops with shanty-like homes dotted around. The concentration of movie stars and rock musicians per square mile is probably the highest in the world. There’s no shortage of money, but there’s also a high craziness quotient which evokes a timeless quality to the Canyon: affluence exists alongside the funky. Joni Mitchell did an album called ‘Ladies of the Canyon’ which established the area as the SoHo of California, only cleaner, richer and more exclusive. And it provides the setting for Lisa Cholodenko’s new film which is called, simply, Laurel Canyon.

Cholodenko was brought up in the Valley and, when she was younger, used to drive through Laurel Canyon on her way to West LA. “I always felt the mystique of going over the hill,” she says. “Nobody ever really told me, but I felt a vibe there, a sort of time warp. It was very distinct from both the Valley and the city. At times, it felt sort of abandoned, but it also felt like all the sub-cultures were still there. When I was younger, someone told me that Houdini had lived there. I was already familiar with Joni Mitchell’s ‘Ladies of the Canyon’ album - everyone was - so I knew something was going on in the Canyon neighbourhood. The area just keeps reinventing itself from the movie-star scene of so many years ago, to the rock scene, to even a porno phase à la Boogie Nights.”

Sam (Christian Bale) and girlfriend Alex (Kate Beckinsale) arrive in the Laurel Canyon house to find that Sam’s mother, Jane (Frances McDormand), is still in residence, finishing an album with British musician Ian (Alessandro Nivola)

Cholodenko’s second feature (after High Art, which screened at Sundance and in the Cannes Directors’ Fortnight in 1998), Laurel Canyon is set in this time-warped world. And its theme is something which used to be a joke in the sixties and seventies but which has inevitably turned into reality: the fact that kids born in the Age of Aquarius are almost always straighter and more conservative than their parents. Kids in the sixties and early seventies rebelled against their conservative parents, and their own kids did the same, drawing on exactly the same motive to move in the opposite direction. It was a way of declaring their own identity.

Jane (Frances McDormand) is a 40-year-old rock chick who has notched up as many failed relationships as she has had hit records. Somehow, though, like the Dylan song, she stays forever young. Her son, Sam (played by Christian Bale), meanwhile, has his sights firmly set on middle age. He has gone to school in the east (to Harvard medical school) and is - well, more than anything else, he is embarrassed by his mother. But when he gets his first post-med-school job at a prestigious psychiatric hospital in LA, he and his girlfriend, Alex (Kate Beckinsale), arrange to live temporarily in Jane’s empty Laurel Canyon home while they look for a place of their own.

But, as usual with Jane, things don’t go quite as planned. Her latest record is running late; she’s given her beach house to a former lover because she feels guilty about having dumped him; and the house in the Canyon is currently the base for Jane’s latest band, a group of British musicians with whose lead singer/songwriter, Ian (Alessandro Nivola), she is conducting a noisily physical affair.

As always, Sam reacts to all this with a mixture of hostility and embarrassment. But he’s out of the house most days, working with extremely disturbed patients in the ‘closed’ ward of a psychiatric hospital. Alex, meanwhile, is trying to finish her dissertation on Drosophilia Genomics (in lay terms, the sexual behaviour of fruit flies) while Jane, Ian and the others work and play around her. Arriving in the Canyon as the straightest of straight arrows, Alex gradually opens up to Jane’s world. And, in doing so, finds herself opening up to Ian.

In the course of redefining their lives, Sam and Alex and Jane inflict suffering on each other, in the way that always happens when people in relationships are developing in different directions and at different speeds. Sam, for example, begins to cross the professional/personal line in a relationship with a fellow Resident, a superficially confident but troubled young Israeli doctor called Sara (Natasha McElhone). And Alex finds the warmth and openness she experiences with Jane and Ian an essential antidote to the academic self-discipline and prim self-control behind which she has always hidden.