So is this the moment Brangelina comes crashing down? Will the Jolie-Pitt union survive the latest revelations in Andrew Morton's new biography, just published in America? This week Jolie, voted the most powerful female celebrity in the world by Forbes magazine, may be holding her breath. Then again she may not.

The nature of a true star is how they handle adversity. And it's telling that just at the height of the scandal caused by Angelina: An Unauthorized Biography, American critics are raving about the 35-year-old's performance in the new action thriller, Salt.

She's being dubbed the female Bond. In Salt she gets shot at, beaten, thrown off trains and planes; she leaps precariously from one tall building to another. The role was written for a man (Tom Cruise), but we've never seen a woman on screen like Evelyn Salt before.

It's easy to forget that Jolie is an actress. Fulfilling Hollywood's love affair with bad girls, she has laid out her life for us to examine like the best sort of performance art. We already knew about the bisexuality, the self-harming and the knives. After winning an Oscar for Girl, Interrupted, she checked herself into a psychiatric institution.

Are there any more dark secrets? Well Morton – who has also written controversial biographies of Cruise and Princess Diana – focuses in in lingering detail on Jolie's past heroin addiction, on S&M parties, and includes sexy photos of Jolie's "shady past". In one she has black tape over her nipples and a dog leash around her neck.

The book won't be published in the UK, thanks to our strict libel laws. But tabloids are speculating Jolie's five-year relationship with Brad Pitt may not survive. Even before she "stole" Pitt from Jennifer Aniston, Morton claims Jolie had targeted married or attached men such as Ethan Hawke, Ralph Fiennes and Mick Jagger. Star magazine quotes a "source" as saying: "For Brad, this could be the final straw."

Personally, I doubt it. Jolie is the queen of reinvention. Protean, brilliant, unstable, she really is a very different form of female celebrity. She has played every role going in her own life (mother, action hero, madwoman), let alone on screen. She can shoot guns and fly a plane. She runs her own production company. She's a humanitarian on close terms with Bill and Kofi.

Men regard her as a sexual fantasy figure (clock the current issue of Vanity Fair, on the cover of which she poses in micro shorts). But women like her too. She's the ultimate girl crush. Partly it's because she's an equal opportunities flirt.

But we also like the way she's reinvented the landscape for women. According to Naomi Wolf, author of The Beauty Myth: "She has created a life narrative that is not just personal. Rather, it is archetypal. And the archetype is one that really, for the first time in modern culture, brings together almost every aspect of female empowerment and liberation."

Most of us only get to play a few carefully selected roles in our lives. Career woman. Mother. Lover. Friend. You have to choose. No woman can have it all, as Emma Thompson claimed with considerable feeling this week.

But Angelina breaks those rules. She's been a home-wrecker and a single mother. She's slept with women. And advocated casual sex ("Meeting a man in a hotel room for a few hours and not seeing that man again for a few months is about what I can handle," she explained after her split from her husband number two, Billy Bob Thornton).

She's made mistakes in public. And yet she still got her fairytale romance – with the ultimate movie star. She has adopted children and proved she can have them biologically. For a woman who has battled addiction and eating disorders, she is the emblem of fertility.

To be honest, Jolie has always been an erratic actress. It takes a strong director to coax a performance like Girl, Interrupted or A Mighty Heart from her. Often we can't get beyond that extraordinary physiognomy.

In 2008's Changeling, where she gives an almost unrecognisable performance as a mother whose child goes missing, it's hard to concentrate because of those erotic red lips. And her role as Colin Farrell's mother in Alexander was an exercise in unintentional camp.

Which is why Salt is a revelation. Her casting makes all the difference in a part that would be completely standard if a man played it. There's a fabulous moment when she's shot and she just grabs a sanitary pad to staunch the wound.

Too often women in spy films are adornments. As Jolie herself put it: "Females in those films rely on being female but we wanted to ignore that. She's just Salt. It's not about being a female and she certainly doesn't use her sexuality to get anything in the film."

I saw an early screening and came out reeling. Jolie is magnificent in a cartoon way. As for the romantic lead, there isn't one. Her husband in the film is a German spider hunter (I know, I know!). Ange makes him pancakes for breakfast and says loving things like: "Get those bugs off the table." Within three minutes, you know he's irrelevant.

Jolie's body is the architecture of the film. The camera scales the cliff-face of that 3D mouth and impossible bone structure. When she wears a skirt suit, it's slit to the thigh. But halfway through she cuts her hair, dons a suit and braces and a latex mask. She is the most convincing lesbian Elvis since kd lang flirted with the role.

In Salt her strength is mind-blowing. She gets muddy and bloody and desperate. You think: how can that rake-thin body crush grown men? Female stars often suffer for their million-dollar bodies – think of Marilyn with her gynaecological problems or Liz Taylor with her tracheotomy. (Even men are not immune: Elvis suffered glaucoma from the black hair dye – he was a natural blond.) But the Jolie body flaunts its vulnerabilities – the tattoos, the scars from self-harm – and comes back stronger every time.

Jolie, now a mother of six, says she read the script for Salt just after giving birth to her twins. "I was at home in my nightgown feeling very soft and maternal, and I flipped through the script and it was all about getting out there and attacking and being very physical and I did feel really funny, in my nightgown in my bedroom, thinking, 'If I can do this, it would be a nice balance.' You know, from being soft and mommy and then going back to work and doing this hard, physical role."

Salt is a new type of action heroine – one beyond gender. We had a flash of it with Demi Moore in GI Jane, but she's gone all femme on us now. Uma Thurman was fabulous in Kill Bill, but she's morphed into yummy mummy roles.

For the British film reviewer Anna Smith: "As a female critic, the most – possibly only – interesting element of Salt is the gender aspect, even if that's semi-accidental. It certainly helps cement Jolie's role as the go-to action girl of choice, arguably improving on the Tomb Raider series. It's refreshing to see a 'female' agent racing to rescue her kidnapped partner, however unlikely that relationship may seem on screen. That this comes as a result of a screenplay originally written for a man is both revealing and disappointing."

Is Salt a good film? Probably not. Does Jolie play a Russian sleeper spy or a loyal FBI girl? Who cares? I lost the plot early on. The film is one mad, bad, un-PC ride. But it's great fun. In the Los Angeles Times, Kenneth Turan argues: "What makes her so good, and what is visible as she deftly navigates the unending silliness of Salt, are traits that add up to a fierce commitment to action, a determination to make the role of a CIA agent who literally and metaphorically takes no prisoners as convincing as she can."

Jolie's take-no-prisoners attitude spills over into her real life. It's telling that Hollywood's most influential TV shows are ignoring Morton's book. For the recent Hollywood premiere of Salt, she and Pitt are alleged to have spent £60,000 on their appearance, including their designer wardrobe and treatments at an exclusive spa.

The whole appearance was "propped" like the most exclusive shoot. Because in many ways Angelina is a starlet in the Old Hollywood model. Think all those other screen queens who go by a single name – Liz, Marilyn, Ava, Garbo. A true star communicates non-verbally. There is an inexplicable but real communication between the camera and the audience. This is not the same thing as great acting. But what all icons share is an unfailing instinct for the dramatics of life on and off screen. As Joan Crawford once said: "If you want to see the girl next door, go next door."

And Angelina has mystique in spades, with her sexuality, beauty and family (her father is the actor Jon Voight; her mother, the late actress Marcheline Bertrand). She's an arch manipulator, great at her own PR and endlessly fascinating.

It's no surprise she has just beaten Catherine Zeta-Jones to play Elizabeth Taylor in the new biopic about her turbulent love life with Richard Burton. Taylor is another superstar with appetites – for sex, love, food, diamonds, men. She adopted children, stole a husband from the resident Hollywood good girl, spent time in hospital, "died" four times. The Vatican denounced her as an "erotic vagrant". And yet Taylor was the first celebrity to speak out for Aids.

Like Taylor, Jolie embraces diversity and dysfunction. She is both Everywoman and the Exotic. On her father's side, she is of Slovak and German descent, and on her mother's side, French Canadian and part Iroquois. She can play black and she can play white.

She's a slate on to which we project our own fears and desires. "But she's not just a tabula rasa, a blank," says the biographer Andrew Wilson. "There's real substance to her. I think she's almost like a third sex. I've never seen that level of sexual aggression, that predatory quality in a female star before."

I ask Wilson, who has written award-winning biographies of Patricia Highsmith and Harold Robbins, if the new Morton book will fatally damage Jolie. "I doubt it. She's such a huge brand. Though what I find fascinating about the Brangelina label is that Brad Pitt is the uninteresting part of the equation."

Anna Smith agrees: "I think she's got enough on-screen charisma and industry power to withstand any mud-slinging from an unauthorised biography. It's likely only to increase fascination with her non-conformist past. And if cinemagoers and studios were going to boycott her for dating a married man, they would have done so already."

But there's something else that endears us to Jolie – makes us hope she will outwit the pack of tabloid hounds currently pursuing her. She is self-invented after a nightmare childhood.

Her relationship with Voight is turbulent - and when a woman avoids her father for years and wants to keep her children away from him, it rings warning bells. In his new book Morton reveals that Jolie's relationship with her mother Marcheline was equally troubled. A few months after her birth, Voight began an affair with a drama student, Stacey Pickren.

After the split, Marcheline rejected Angelina – because she looked strikingly like her father. According to her babysitter, Angelina was moved to the fifth floor of a Beverly Hills apartment block where "like some kind of infant Rapunzel locked in a tower", she was looked after for the first two years by nannies (mostly out-of-work actors), while her mother lived downstairs with her brother.

Even when Marcheline eventually brought Angelina back into the fold, the pair became more like sisters than mother and daughter. When Angelina had her first boyfriend at 14, Marcheline encouraged them to start living together at her home. Throughout her teens she suffered from anorexia, took drugs, self-harmed.

Hardly surprising then if the adult Jolie, with her own abandonment issues, has a healthy disrespect for the traditional nuclear family. Arguably that rainbow nomadic family is Jolie's greatest creation.

Female stars tend to get punished for being human. Angelina proves you can literally be too much. Admit what you want – and take it unapologetically. And we, dear reader, get to live that huge operatic life by proxy. Because let's be honest, no one actually wants to be Angelina – too many screaming babies, too many hotel rooms. Just as no sane woman really wants to look like Angelina. That slender form – head too big for her body, mad goddess hair – doesn't look exactly healthy.

To paraphrase the novelist Josephine Hart, damaged people are dangerous because they know they can survive. But Jolie is the future. Our next Big Action Hero. With Arnold Schwarzenegger retired and Tom Cruise seemingly no longer a draw for audiences, there is a gap to fill.

For her part, Jolie is always threatening to retire young. But I'd argue that this is one star who can afford to get old on screen. I can't wait to see what she's like at 40, 50, even 70. Humanitarian, mother, deranged daughter, gender-defying actress – has there ever been a girl like Angelina?