Books: Upstaged by Toby, the sapient pig

A search for the soul in the tale of an 18th-century freak

The Giant O'Brien

by Hilary Mantel Fourth Estate pounds 14.99

In a glass case in the museum of the Royal College of Surgeons hang the clean brown bones of Charles Byrne. You can inspect them between the hours of 10 and 5, Monday to Friday. Byrne was an Irishman who exhibited himself for money in London in 1782 and died there, aged 22, the following year. At 7'10" he was, even by modern standards, a giant.

Hilary Mantel has taken these bare bones and fleshed them out in an extraordinary novel written without a superfluous or inappropriate word. is a model of restraint, authority and intense lyricism, rich and resonant. It is hard to resist reading it aloud for the beauty of its language, while its complex morality exercises the mind long after the book is closed.

There was doubt about his real name, but for Mantel he was born O'Brien. Travelling through a landscape scarred by fearful poverty, he resolves to try his luck in England. He intends to return, rich enough to rebuild Mulroney's tumbledown tavern in imperishable stone, with columns and marble fireplaces, marquetry tables and lyre-backed chairs. The wily Joe Vance becomes his agent and rechristens him Byrne, considering it a more select name. Attended by a ragamuffin crew, they set off across the sea, hungry for fame, fortune and - particularly - food.

At this time there lived in London the famous Scottish surgeon and anatomist John Hunter. Mantel depicts him as the epitome of the desiccated scientist, a sinister, obsessive man driven by a relentless need to discover everything there is to be known, particularly about human and animal biology. He sees no harm in injecting himself with syphilis, the better to study the course of the disease, and he pays grave-robbers to follow weeping women and bring him the newly dead. He is fascinated by the soul - whether it exists and, if so, what it weighs. He has a large hoard of skulls and skeletons: he resolves to add the Giant to his collection.

If Hunter embodies ice-cold science, the Giant is all wisdom and world- weary melancholy. He knows Hunter and dislikes him. "He is gruff, unlettered, rude, whereas I am learned, poetical and fond of civil company." O'Brien's stories run a golden thread through the book, weaving folk tales, ballads and fantasy into the steamy squalor of Georgian London. He tells of forests and changelings, pig-babies and wicked elves. His hearers are appreciative: "It is seldom, in these debased days," says one, "we are able to hear a tale told in the antique fashion by a gent of such proportions". Into the broad weft of the narrative are also woven the fortunes of the two men, becoming increasingly intertwined as the Giant grows ever more aware of his approaching death and as Hunter's determination to have his body intensifies.

Around the two central figures scurry the thieves, whores, freaks and crooks who scratch a living in the capital. London, says Mantel, is like the sea and the gallows - it refuses no-one - but no spectacle, however rare, stays interesting for long. O'Brien's public turns its attention to Tibor the Terrible Tartar, to the spotted Boy, to the Human Pincushion and to Toby, the sapient pig. The Giant's hangers-on, feeling the pinch of poverty, encounter the grasping servant of the anatomist. An infamous deal is struck, though the Giant, terrified that dissection will deny him resurrection, begs to be buried at sea in an iron casket. He knows there is little chance. Everything fails, he fears, "reason, and harvests and the human heart".

Hilary Mantel is a novelist of remarkable diversity: her subjects range across continents and centuries but her concerns remain the same. She writes about curiosity, companionship, ambition, art, love, death and eternity. She writes with wit, compassion and great elegance. Her books never fail to surprise, nor to delight: in this one she is at her very best - so far.