In Arabian Nights, by Tahir Shah

There comes a time when even travel writers no longer feel like travelling; they return home, exhausted, to explore their roots. Tahir Shah, who has described his exotic adventures in Peru, India and Ethiopia, has reached that stage. His previous book, The Caliph's House, began the process, describing life in his home in Casablanca. But a recent experience in Pakistan's North West frontier accelerated it.

Arrested with his film crew on suspicion of spying for al-Qa'ida, he was held in an interrogation centre called "The Farm" and subjected to weeks of sustained cross-questioning. What sustained him were memories of the stories he was told in Morocco as a child.

Tahir Shah is a storyteller's son; his Afghan father Idries Shah achieved fame in the West with The Way of the Sufi, collected Arab stories, and came from a long line of writers. While Tahir has told many a traveller's tale over 12 books, this is perhaps the first time he comes so consciously into his family's inheritance.

Exiled in England, Idries had been unable to take Tahir and his sisters back to troubled Afghanistan, so instead had taken them to Morocco – to which Tahir now returns with his own children, following his father's obsession with the importance of fable and finding "the story in your heart". He encounters five boys outside a cinema in Tangier: they are pooling their slender resources to buy a ticket for the youngest. When Shah asks why, they reply that it is because he has the best memory, so can recite the film to them afterwards.

This is a book about the power of memory and the spoken word – particularly the Arab word. The interlaced stories of the Arabian Nights serve as a model for Shah's wandering minstelry. From the delightful domestic chaos of the Caliph's house, with its disruptive djinns, he criss-crosses Morocco searching out those storytellers, often illiterate or blind, who still practise the old oral traditions.

The fables he finds are as memorable for the closeness with which their custodians treasure them as for the simple parables they tell. For the Sufis, "stories are a kind of key, a catalyst, a device to help humanity think in a certain way, to wake us from our sleep". Only a hair's breadth divides the inspired Sufi saying and the platitude – and just occasionally, with lines like "the journey is nothing more than a path to a destination," Shah is in danger of crossing it. But in the main this is an inspired and often funny search, told with his usual staccato rhythm and unfailing ear for dialogue: "'How do you know I've come from England?' 'Because you look too pale to be Moroccan and too content to be French.'"

Although he takes care not to labour the point, the way of the Sufi is under threat: from Dagestan to Morocco, their shrines are desecrated as the Wahhabi fundamentalists target them, enraged by the "holy fools" who preach religious tolerance and believe that a joke and a fable might lead to enlightenment. This beguiling book shows that there has never been a better time to value the free-thinking, story-telling tradition within Islam.

Hugh Thomson's 'Tequila Oil', a memoir about getting lost in Mexico, will be published shortly by Weidenfeld & Nicolson