Ollie, by Stephen Venables

On 11 April 1994, the Venables family left a paediatric clinic in Bath to start a new life "in a foreign country called Autism". It hardly proved a settled existence; more a baffling, heart-rending trek beset with frustrations, endless hospital visits, and interludes of joy which came to end, for Ollie at least, on 16 October 2003. Having fought leukaemia and a brain tumour operation, his frail body had gone into meltdown.

Two weeks later, Stephen Venables, his wife Rosie and second son Edmond began their own return from that "foreign country" with a memorial service at Bath Abbey, attended not only by family and friends but by many specialists and carers who had assisted Ollie. One of the positive revelations of Ollie's story is of how many different lives can be touched by one small boy, and how compassionate nearly all those individuals are. In that respect, Ollie is a gratifying reaffirmation of basic human kindness.

Venables is respected worldwide as a mountaineer and as author of a clutch of books that portray the climbing game without the macho hyperbole. In 1998 he became the first Briton to reach the summit of Everest unaided by bottled oxygen, and came pretty close to death in the process.

With Ollie's diagnosis of having autism, Venables became caught up in a very different drama. Though as a toddler Ollie suffered gastric problems, disturbed sleep and viruses, in his speech and physical development he had been quite advanced. As the gift of speech deserted Ollie, his parents became convinced that his MMR vaccinationat 15 months had been an important factor in the onset of autism.

Cruel insult was added to the injury when Ollie developed leukaemia. He survived chemotherapy only to have a relapse two years later and begin another cycle. Venables lost count of the times he accompanied his son into an operating theatre, all the more distressing for both in the speech-denying fog of autism.

Yet Ollie is not a bleak book. There are episodes of exuberant joy and there is the cultured background of Bath, where Ollie - an agile escaper - bounds free and trouserless. Venables claims to have found this journey with his son "far more compelling than any expedition". And so it proves as a book: Ollie's courageous story is certainly more compelling than a climbing narrative, though Venables, with his self-deprecating wit, would probably say that was setting the bar rather low.