Robyn Davidson is best known for her international best seller Tracks about her trek across 2,700 kilometres of Australian desert in 1977. Her new book, Unfinished Woman, tells of another journey, this time into her past. It is mostly, she says, about her mother, who died by suicide in 1961, when the author was 11 years old.

Using a fragmented narrative, Davidson moves back and forth through time, and often circles back to her childhood years in Mooloolah, Queensland. Her mother began to suffer from severe clinical depression and the family moved to Brisbane to be closer to doctors. One afternoon, Davidson came home from school to be told her mother was dead.

Davidson squeezes a lifetime into almost 300 pages and much seems unrelated to her mother, who remained a shadowy figure. The person who stood out for me was her sister, Margaret, who is six years older. Siblings after all are most people’s longest-lasting relationships and can have just as much or more influence on our lives than our parents.

When they were children, Davidson both worshiped and feared her sister. During their fights, Davidson wondered if she would die, but her tears were not from her sister’s punches but her words. ‘Her nails dig into my arm, the air goes out of my stomach, and the sneering, loathing refrain pours down: “useless, ugly, stupid”.’

This seems more than the rough and tumble of sibling rivalry and Davidson is relieved when Margaret goes to boarding school as there would be ‘no more bullying’. Her sister’s contempt leaves a deep mark and, tellingly, Davidson says her desert walk gave her a kind of integration, and ‘proof that “useless ugly stupid” was not all there was.’

Davidson spent several decades overseas, mostly in London and India. She provides few details of her tumultuous relationship with Salman Rushdie in her mid-30s. She gives more details of her partnership with Narendra Singh Bhati, a Rajput aristocrat. He drank heavily daily, but Davidson spurns the use of the term alcoholic (‘a Western concept’, she quips).

Davidson and her sister become estranged as adults. They met up in 1996, but the reunion was not happy. Davidson says her sister’s voice was cold and bitter and vibrated with ‘loathing ? the longing to crush something loathsome.’ Davidson excuses her sister’s anger and says Margaret is acting out of her own loss and grieving.

A fascinating book, but I felt increasingly frustrated by Davidson’s rationalizing and excusing of bad behaviours.