IMAGINE being phoned by a cousin you barely know, someone who lives more than 4,000 miles away. He tells you the grandmother you never met - the one who was sent off to a mental institution in her early 20s, in 1925, shortly after having three babies within 35 months; the grandmother who was never spoken of and so had remained in your imagination as a "dribbling she monster" because she was supposed to be violent has been sighted by an acquaintance.

Imagine being told by your semi stranger of a cousin your grandmother had been recognised by someone able to report that the old lady, now 95, was living in a Memphis nursing home and had been there, unvisited by the family, for 11 years.

Imagine you are a black American and because of the violations committed against many black Americans, some of the members of your own family are white skinned, pale enough to be thought white. Imagine the confusions this causes. Imagine your long forgotten grandmother herself is white, though she speaks with the voice of a Southern Black.

What would you do? Would you care? After all, the old lady was the mother of the father you hardly knew; the father who had divorced your mother when you were still a baby; the father who had committed suicide almost 40 years earlier. So this grandmother does not belong to you or your past.

Would you listen to this strange story with detachment? Would a sad story about a stranger mean anything to you at all? Would you hang up the phone and continue with your own life? Or would you try to help an ancient woman you never knew, largely because she was old and alone and alive and probably never was insane in the first place?

Novelist Marsha Hunt - also actress and formerly London radio chat show host; dancer/singer/songwriter; owner of the face that inspired the 1960s catch cry "Black is Beautiful" and one of the most enduring visual icons of that time - received such a call one day in the summer of 1991.

She was staying at her house in a French village about 90 miles north of Paris, and working on Free, her second novel. The call was unexpected but in keeping with an almost supernatural happening in her house. "The baby picture of my dead father had been mysteriously fading for three days when the phone rang that Saturday. I'm still not sure if this story starts with the phone call or the spooky way Blair's baby image was disappearing," she writes.

She had never even seen a photograph of her grandmother until she took her daughter to meet Blair Hunt Senior, Marsha Hunt's grandfather and the husband of the mental patient. He was 89 and was to die the following year. Living in Memphis, Mr Hunt was not only another relative Hunt barely knew, but he belonged to a foreign culture, that of the American South.

Showing her a photograph of her grandmother, the old man commented: "My poor, dear sick wife is still in hospital, incurably insane". Mr Hunt added that his wife's condition was hereditary. The image of that first photograph, a high school graduate snap of a pretty young girl, was in Hunt's mind as she reflected over the phone call. It was the beginning of an incredible quest not only to track down a forgotten woman, but to give her a past and to unravel the mystery of a lost life.

Hunt's journey into a family history which was barely part of her own experience is recorded with urgency and candour in her new book. Repossessing Ernestine, a remarkable account which not only moves the reader to anger, but should remind most people of what being human and humane is really about. One of the most unnerving moments in a shocking tale filtered through Hunt's compassion occurs late in the book when her grandmother, by now sitting contentedly in a Kent nursing home, exchanges her experiences with the other old people. An elderly man speaks about his war years but Ernestine, when asked what important things happened in her life - a life which was taken from her - replies: "I got killed."

There must be some irony in the fact that having heroically worked to right the many wrongs committed against her grandmother - not least the indifference expressed by the old lady's only surviving son - Hunt herself is still known by most as a young woman who personified swinging London; the girl with a small role in the musical Hair who came to personify the show.

Her two novels' to date prove that she is an accomplished writer, yet still she has to contend - in some memories - with being the woman who sued Mick Jagger to acknowledge paternity of their daughter. "It is always important to remember that there is absolutely nothing you can do about other people's perceptions of you," she announces.

INITIALLY treated as an exotic outsider in London - "I saw myself as a singer/songwriter; they wanted to photograph me because of the way I looked. I reckoned let them, I just went on singing". Hunt had to leave America to be seen as an American. In the States, she is seen first as a black and points out: "In parts of LA, I still almost feel that I should say to people, don't worry, I'm not going to steal anything from your store.

Race is still an issue, "and whoever says selves". She says growing up in a world in which different shades of brown skin tone determine status hones your survival instincts. Even as a confident woman - a novelist and performer with an international profile - Hunt, who appeared with the Royal Shakespeare Company, was still conscious of being a black woman accompanying her white grandmother.

Sitting at a large window in a Co Wicklow hotel, Marsha Hunt is a relaxed, friendly woman with fine, almost oriental features, a wayward mane of black candyfloss hair, a schoolgirl's smile and a natural casual elegance - although she stresses "I'm dressed like this for the interview, when I'm writing I look a lot different, I'm a mess". Having lived alone for so much of her life, she is now in love and living with film maker Alan Gilsenan in Wicklow.

Gesturing at the view out over the glen, which is slightly spoiled by the traffic racing by, she says cheerfully: "I love being able to look out forever - this is like where I write in France." Her accent moves between formal, deliberate English and warm American, she is a shrewd, perceptive reader; funny and exact, she enjoys discussing books. Because she is black and American, commentators have grouped her novels, Joy (1990) and Free (1992) alongside the work of Toni Morrison, Maya Angelou and Alice Walker. "It's crazy. There's only one Toni Morrison.

It is also inaccurate. As a novelist, Hunt has her own distinct voice: Joy is a first person narrative written in a sharp, vernacular prose (and since adapted by Karis Jagger and her mother for Hunt's performance at the 1994 Edinburgh Festival), while Free is a darker, more formal literary work exploring race and the hypocritical legacy of post slavery America. She says of her fiction: "I'm interested in storytelling but I also look to music. The repetition and the rhythms." No matter how good these novels - and they are - they still have to compete with the 1960s and 1970s life of their author.

Far smaller than expected ("I'm tiny") she is 49, ("almost 50") and looks about 30. Being caught in such a physical time warp means little to her: "Nature has this sneaky way of catching up on you. All my family are like this, no lines - but they do show up eventually. They'll get me too, you'll see. Suddenly everything just falls apart." And she laughs, not for the first time and certainly not for the last.

Standing patiently outside in the cold while the photographer is busy, she smiles and is grateful he doesn't want her to hold the handrail leading down the steps. "The rail's freezing. Hey, don't I get a chance to comb my hair?"

About two minutes after meeting her, it is easy to see why she would drop everything and help her grandmother discover some semblance of a life so near the end of one destroyed by others. Still very American despite having left the country almost 30 years ago, Hunt is wise: "Hell, I'm supposed to be, I've lived a long time. Living teaches you something about life." She is also fair. The sheer injustice of what had happened to her grandmother while still a young woman outraged her. She may have gone to rescue a stranger, the mother of a father she hardly knew, but "blood is blood, the bloodline is a powerful thing".

RAISED by her mother, her aunt and her maternal grandmother, Hunt realised at an early age that she had to do well better than well. When the family moved to California when she was 14, she not only adjusted to another world California is very different to Philadelphia - she was academically successful enough to earn a place at Berkeley. Asked what the young Marsha was like, she laughingly answers: "I was good; I was a good girl". That she was capable of rebellion is written all over her smiling face, but also obvious is her compassion.

Hunt responds to people as individuals. She is a habitual carer with a mothering instinct. Practical and maternal, she worries about people being cold, hungry or tired; it is not an oppressive kindness. She laughs on being told she seems too sensible to have been involved in the rock business. Concerned about the shortage of black British born writers, she instituted a literary prize. The Saga Prize, which was first awarded last year, and the first winner of which, a novel by a young black man, will be published by Virago in June.

Recalling the moment she made contact with Ernestine, Hunt replicates the dense Southern accent of the woman who answered the phone. "Lord ha mercy! I have been prayin' some of Miss Hunt's people would come for her. Yes I have, been prayin' and prayin'. Cause she ain't had nobody all these years. No. Not nobody."

Hunt's wisdom and her survival instincts come from growing up a black girl in America - in Philadelphia, a city divided by an awesome sense of history and of race. It is a place where so much of American history was shaped. As Hunt remarks in her autobiography, Real Life: "To be coloured in 1946 was to be economically confined and socially isolated. Segregation laws did not exist everywhere, but the fact that they were upheld in many states reminded everybody who was boss." But asking about her life is not easy; she does not want to talk about it, saying it has already been well documented. Too good natured to be openly exasperated, Hunt is nonetheless understandably weary of the public's interest in her long over love affair with Mick Jagger. The rock star is the father of Hunt's only child, her daughter Karis, the eldest of Jagger's five children. Battling for her daughter's rights in court, she raised her alone. By the time Hunt wrote her commissioned autobiography, Karis was 16 and Hunt was writing about events then in the past. "They're even more past now."

So much more has happened to her since then; her daughter has graduated from Yale; Jagger and Marsha Hunt are friendly now. "Although I know the public would rather if we weren't." She does not approve of people speaking about their children as if they were either possessions or extensions of themselves. "My daughter is grown up, she has a life of her own. She doesn't need me to speak for her.

An entertaining, witty talker, Hunt is concerned with the now. Still, she enjoys speaking about motherhood, an experience in which she delighted, although throughout she was struggling to mother her child while also pursuing a multi sided, insecure career.

Even to anyone with no interest in the 1960s swinging or otherwise Hunt's autobiography is interesting because it is an account of a real life: how one woman managed to be a good mother through an impressive and endearing combination of energy, enthusiasm, determination and impulsiveness. On the cover of the recently re issued paperback version of Real Life is the famous Justin de Villeneuve photograph of Hunt wearing, her dramatic "busby" Afro.

What does that picture mean to her now? "It's a nice piece of history."

Written when she was 39 Hunt's autobiography was criticised by many for not being a racy "kiss and tell". It came out, of an interview by the poet, and subsequently Larkin biographer, Andrew Motion.

"He was researching his book about the Lamberts the famously wild, eccentric English clan and Kit had been my manager," she says. "He suggested I write my biography and commissioned me to do it."

Setting out to tell as much as possible of the truth without being too explicit, her story is the story of its time. While she is not a campaigning or polemical person, her honest description of her experiences emerges as social history as much as autobiography.

This is even more true of Repossessing Ernestine, and goes beyond her own awareness of being told that these kinds of things used to happen to women. In the course of her investigations, Hunt discovered that all of her grandmother's teeth had been extracted.

IT is an amazing story, full of twists and turns, Dickensian coincidences and discoveries. Jet lag, dead ends, money problems, all conspire against her; she finds out that her own father had remarried six weeks before his suicide; one of the women working at the mental institution appears willing to talk about Ernestine but when Marsha returns the next day she is told that the woman has dropped dead in a local market . . .

Ernestine's guardian is none other than Ms Harry Mae Simmons, her own husband's mistress of some 47 years standing. When Marsha, despairing of the conditions in the Memphis home, decides to bring her grandmother back to England with her, it is not easy. The old lady does not have a passport because black births were not being registered at the time she was born. Luckily, she did feature in a census Hunt remembered noticing while researching old newspapers.

Permission to leave the country has to be granted by the guardian. Conscious that she can not care for the old lady in her fourth floor flat, Hunt settles her in an expensive local home only to discover that Harry Mac Simmons, who as guardian was obliged to meet the costs of care in the US, has decided not to meet costs in the UK.

Finally, Hunt has no option but to bring her grandmother back to the States and finding no consolation in the knowledge that she has tried, is devastated by an overwhelming feeling of failure.

Although she has lived the quest and written about it, Hunt has not lost her own sense of wonder at the entire fantastical tale, another surreal chapter in a fast moving life dominated by the unexpected. "Yes there is one thing certain about life - you never know what is going to happen next, do you?"