Fi: A Memoir of My Son by Alexandra Fuller review – to the edge of reason

Alexandra Fuller was in a pickup truck in Wyoming with her girlfriend, Till, when her mobile beeped. The relationship was newish and fraught: Till was young, with “skin like alabaster”, but had issues – neediness, drugs, self-harm. Alexandra (“Bobo” as everyone knew her) was still recovering from a broken relationship and didn’t feel cut out for intimacy.

The dramas between them were intense but paled into insignificance as Fuller turned and saw missed calls from her ex-husband, Charlie. The news was terrible: their son Fi, just 21, had died in his sleep. “Fi died and everything that I’d believed in until then blinked out with him.”

Fi had just come back from Argentina, where, stressed by exams and late nights, he’d had an inexplicable seizure. On return to Wyoming he seemed fine, just a little tired. He’d always been sporty – tennis, lacrosse, hockey, mountain-climbing. He was smart and self-aware, too, and great company for his two sisters, “the perfect son”. Now he was gone and his mother was in “unimaginable agony”, “the most aloneness I’d ever known”.

The book’s subtitle is misleading: this is less the story of Fi (of whose death Fuller wrote in the epilogue to her previous – third – family memoir, Travel Light, Move Fast ) than of his mother’s grief. She’d had more than her share already: in childhood, the deaths of three of her four siblings (one from meningitis, one at only a week old, the other a younger sister who drowned while in her care), more recently the death of her father and divorce from Charlie. But losing Fi was on a different scale, “the worst thing I’d ever felt. Unimaginable”.

She doesn’t want to know why Fi died, won’t give a blood sample to see if she carries ‘the gene, the poison, the error’ that killed him

Grief drives her to the edge of reason. She doesn’t want to know why Fi died – won’t read the autopsy report or look at his health records or meet doctors; won’t give a blood sample to see if she carries “the gene, the poison, the error” that killed him. Instead she talks to the hummingbirds and eagles that appear in the days after his death, which her magical thinking tells her might carry messages to Fi. His presence lies not in what’s left behind – the ashes she feels through, which are “grainier than expected” – but in the natural world: birds, storms, a doe, a double rainbow, all of which are somehow Fi.

Friends fly in to see her and are kind, supportive, full of good advice. They’re consolation for the non-appearance at Fi’s funeral of her mother and sister, who haven’t forgiven her for what she wrote about the family in her award winning 2002 memoir Don’t Let’s Go to the Dogs Tonight. But only the wild is conducive to her grief. On the first full moon after Fi’s death, she hikes up to camp by a mountain lake. And on the second full moon, Till tows her “sheep wagon” to a high meadow so that Fuller can set up a “grief camp” run on a “boarding school schedule”, with eight hours of writing a day.

What she needs is solitude and discipline, with “Till fading in and out – more or less helpful, more or less unhinged”. The regime takes its toll: her weight drops from nine to seven stone and she’s plagued by guilt at the tiger mother she had been, often away on writing assignments on her children’s birthdays or school holidays. “Who’ll look after them?” she’d be asked. “Oh, they’ll be all right,” she’d reply, “They’ve got assault rifles.”

Life writers often want to be likable, for readers to sit beside them and empathise. Fuller’s not in that camp: rawly bereft, she doesn’t care how she comes across. Her exes have told her what a force of nature she is and she owns up to being bossy, overbearing, “a provocateur and know-it-all”. It’s no easy ride in her company, but that’s the point: she doesn’t spare us the pain inflicted by “the sharp knife of a short life”. Equally, she won’t react in the same way as her mother, whose loss of three children led to depression and alcoholism.

Related: Alexandra Fuller’s African childhood

There are several phases in Fuller’s recovery programme: massages from a naturopath in Taos; a beach holiday in Hawaii with her daughters Sarah and Cecily (plus Till); a week in a nonprofit grief sanctuary in New Mexico; 10 days at a meditation centre in Canada, where speaking is forbidden. At one point, miraculously, she hears her daughters laugh, and after a farcical episode with an officious cop she and Till laugh too. At the end, she’s living in the Rockies surrounded by elks, bears, snakes and porcupines. It’s not that she has found Fi, but she has found “a settling place”, an appeasement of sorts in the wilderness, “like being in the arms of a trusted old lover”.

• Fi: A Memoir of My Son by Alexandra Fuller is published by Jonathan Cape (£18.99). To support the Guardian and Observer order your copy at guardianbookshop.com . Delivery charges may apply.