About the time her international bestseller The House of the Spirits was being filmed with Jeremy Irons, Isabel Allende was on a promo tour in Madrid of her third novel. So when her married daughter threw a wobbly and missed the book launch because she was weepy and feverish, Isabel thought that she was a hypochondriac. The next day Paula slipped into a coma, and Isabel Allende chucked in being a world-famous author to will her daughter back to life. At the Madrid intensive care unit, her agent handed her the lined yellow pads she favours for writing and told her to record the experience. The result is a painfully honest love story for a child that will bring tears to your eyes.

Allende doesn’t really explain Paula’s life-threatening condition, porphyria, which the hypochondriac must look up in a medical encyclopedia to discover that it is an ‘inborn error of metabolism resulting in the excretion of an abnormal pigment in the urine and characterised by great pain, abnormal skin pigmentation and photosensitivity’. When Paula wants to drink she must wait until someone squirts water from a syringe into a tube in her stomach. She has a hole in her throat and the air doesn’t reach her mouth. Her lips are always dry. If her mother moistens them, the liquid can go into her lungs. ‘The sordidness eats holes in her heart,’ Isabel observes forlornly. Her grief is truly awful, seeking forgiveness as she asks herself, her child and the readers: ‘How can I shake this guilt? When you mentioned the porphyria I thought you were exaggerating and instead of seeking further help I trusted those people in white. I handed my daughter over without hesitation. It isn’t possible to go back in time. I must not keep looking back yet I can’t stop doing it, it’s an obsession.’ Paula no longer recognises her mother, who struggles to teach her to squeeze her hand, one for yes, two for no while admitting that it is a fruitless effort. On the screen there are just two black holes where her brain should be. She is like a plant, the doctors say, but her mother believes she is like an insect in a cocoon, and she asks herself what kind of butterfly will emerge when Paula awakes.

Entirely without whimsy or sentiment – ‘I know how much you hate that, Paula’ – it is also the portrait of a modern mother. Allende, Eighties big-time grosser in that curious mix of peep-show, predictions and purple prose called magic realism, has turned autobiographer. Yet again, she hits the Zeitgeist. For gutsy, gripping tabloid journalism is the mood of the moment. Molested by a sailor when she was eight, married at twenty to a man she respected (Paula’s father), a runaway mother who left her two children behind when she went to Spain with a lover, a disillusioned divorcee who subsequently met the man she loves, this story of raging desires is scandalous.

She certainly proves wrong the poet Pablo Neruda, who told her after two bottles of wine when she wanted to interview him that she must be the worst journalist in Chile: ‘You are incapable of being objective, you place yourself at the centre of everything you do … I suspect you’re not beyond fibbing, and when you don’t have news you invent it.’ Since in literature those defects are virtues, he urged her to write novels. What a waste. Her novels pale by comparison with this astonishingly revelatory piece of journalism. Here you will find concise and vivid portraits of Lebanon before Beirut blew up, of a Chilean childhood crossing the cordillera of the Andes, and of Colombia, where she was exiled after her relative Allende’s deposition and death when the military junta took over Chile. Her account of that troubled time is brilliant, every bit as good as the fictional portrait of dictatorship in South American climes, Autumn of the Patriarch by her fellow magician and realist, Gabriel García Márquez. Amusingly, she wrote to ask President Allende what he wanted for Christmas at a time when the right-wingers were barricading the streets and the peso was in freefall, and she records his exasperated reply: ‘Isabel, don’t ask me bullshit like that.’

Of course, in her world there had to be a Shelley von Strunckel. During her exile from Chile, Isabel Allende met a celebrated seer in Buenos Aires, who held her hands and made four predictions: ‘There will be a blood bath in your country; you will be motionless or paralysed for a long time; your only path is writing; one of your children will be known in many parts of the world.’ This gives Isabel Allende hope, that most undermining of emotions: ‘You will not die, Paula, since you haven’t lived out your destiny.’ Mummy, until now, has never shared her past: ‘It is my innermost garden, a place not even my most intimate lover has glimpsed. Take it, Paula, perhaps it will be of some use to you because I fear that yours no longer exists, lost somewhere during your long sleep, and no one can live without memories.’

The memories she shares with us of Paula are sweet: the child who hid her grandmother’s bottles among the dahlias in the garden, the girl who unflinchingly told her mother why she shouldn’t go to Barcelona with a Spanish poet, the young woman who kept up a loving relationship with her father and her brother, the genetically cursed porphyric who wrote in her early twenties a letter to be opened after her death, the Sleeping Beauty that failed to awaken to her beloved husband’s kisses. Paula lay comatose in the Madrid hospital until her mother freed her from the catheters, tubes, drips and breathing machines to fly her to California, where she took care of her until she died.