The man who championed cold logic - and fairies

Teller of Tales: the life of Arthur Conan Doyle, by Daniel Stashower (Allen Lane, £18.99)

"In December of 1899, Conan Doyle announced to his startled family that he wished to join the army and fight the Boers." Daniel Stashower's buoyant new biography is not, as you might think, referring to an impulsive adolescent in the grip of patriotic feeling, but to a burly man of 40, a GP, father of two and celebrated author.

Conan Doyle succeeded in getting into the Boer War, but not in a military capacity. His medical training took him as far as Bloemfontein early in 1900. Instead of a longed-for engagement on the battlefield, he found himself in the middle of a typhoid epidemic.

The exceptionally well-stocked life of Sir Arthur Conan Doyle, with its Boys' Own Paper gloss and pungent contradictions, has proved irresistible to a string of biographers. Can the story stand retelling? Well, like the best of his works, it always adds up to a rattling good read. Stashower has written a bright, businesslike and bracing life.

Stashower claims to be uniquely open-minded about his subject's later years, when the level-headed creator of the greatest fictional detective had grown into a weird old man who believed in fairies. It should be possible to treat this aspect of Conan Doyle's mind "with sympathy rather than derision". However, though his tone is scrupulously friendly, he is clearly on the side of scepticism.

The Cottingley fairies episode, when the elderly Conan Doyle was taken in by a fairy photograph that looks to modern eyes incapable of fooling a six-year-old, was the last straw for certain friends and admirers who had previously swallowed his spiritualist leanings. "Poor Sherlock Holmes - Hopelessly Crazy?" speculated the Strand magazine, once the primary outlet for the immortal detective.

Indeed, what has always fascinated Holmes aficionados is the discrepancy between the detective as embodiment of supreme cognitive powers, and the author's infatuation with hocus-pocus. On the one hand, you have Holmes drawing Watson's attention to a well-worn hat - "not as a battered billycock, but as an intellectual problem" - and on the other the inference that Conan Doyle's own headgear had become a bonnet with a bee in it. However, a belief in spiritualism did not descend suddenly, but had been growing to fill the vacuum caused by his abandonment of Catholicism after his Jesuit schooling.

Conan Doyle was born in Edinburgh in 1859, one of seven surviving children of a mad alcoholic artist of Irish descent, and a resolute mother - the Ma'am. As a medical student in Edinburgh, he came in contact with the formidable Dr Joseph Bell, whose powers of observation were later transferred to Holmes. By the time A Study in Scarlet came out in 1887, its author was a young doctor, married and practising in Southsea. There was some idea that he might specialise as an oculist, long before he turned into an occultist.

A taste for adventure had already been gratified by a trip on board a whaling ship; but Conan Doyle's prodigious energies propelled him in many directions: not only prolific authorship, but politics, athletic exploits, motoring, real-life crime-solving and crusades for cherished causes. In 1909, he was president of the Divorce Law Reform Union - not that this had any bearing on his own situation. While his first wife, Louisa, was dying of TB, a second wife waited in the wings.

When Agatha Christie staged her famous disappearance in 1926, Conan Doyle was promptly on the case enlisting psychic help, while the 33-year-old Dorothy L Sayers was among civilian volunteers in the search - an intriguing convergence of luminaries. Daniel Stashower isn't one to overlook such a pleasing coincidence. Conan Doyle, though, remains an enigma: the perfect English gentleman, down to his walrus moustache, who was actually Scots-Irish; the upholder of cold reason who ended in thrall to mumbo-jumbo. It is, as Holmes once observed to Watson, "a most singular and whimsical problem".

The reviewer has edited the new 'Oxford Book of Detective Stories'