BOOK REVIEW / Ancient art of true crime

"IT was a death that began it all and another death that led us on," begins Morality Play, Barry Unsworth's successor to his 1992 Booker Prize-sharer. lt's a sober-looking book (dark cover, dullish title), but it turns out to be that rare and precious thing: a perfect novel.

A daring claim, but I make it because - given its intent - this book dazzles on every level. It's lyrically surprising, unforgettably credible, darkly challenging. You succumb happily on page one and stay in thrall right up to the quick, bruising end.

It's the dead of winter in the late 14th century and England is a rough and shadowy place, flayed by plague and moral corruption. The fatal, black swellings of the former are plain to see, but symptoms of the latter are all too easily masked by the easy secrecy of wealth and power.

Nicholas Barber, a 23-year-old whose lively, nervy goodness permeates the tale, has gone walkabout from his monastery. After singing, gambling and even stumbling into fornication ("I was hoping she would give me to eat, but she was too hungry and hot"), he falls in with a troupe of travelling players. Why not? He has nothing left to lose but his tonsure.

Arriving in a strange town, the players decide that instead of performing the usual God/Satan drama they'll re-enact a play about Thomas Wells - the "true" story of a child whose murdered body has recently been found dumped by the roadside. A deaf and dumb girl is soon to hang for it.

At first, not questioning the prisoner's guilt, the players simply aim to present the locals with entertainment - "plays from stories that happen in our lives" - a prophetic forerunner of the television soap, perhaps. But Life and Art are never that simple, and the resulting drama is more Crimewatch than Coronation Street.

Improvising from the barest sprinkling of supposed facts, the players find themselves reaching unpalatable truths which spring directly from their empathy with their roles. "It has seemed to me like dreaming," Barber struggles to explain. "The player is himself and another... From this come thoughts and words that outside the play he would not readily admit to his mind."

The True Play of Thomas Wells becomes stronger than its creators, provoking the market-place crowds with details that simply don't add up. This may do wonders for box office, but the spooky momentum of the real-life murder play also commits the unwitting players to uncovering the true killer - a dangerous business, since he is clearly still at large.

But this is no mere historical thriller. Its plot is more uncomfortable, its meanings infinitely darker. The brave detail of the writing plunges us into the terror of a time when life was a quick, hungry spell lodged between cradle and grave. Wolves haunt the forest, hooves clatter across frozen yards, castle chambers are silent but for the "scratch of talons on leather".

It's a novel of intense and memorable physical sensation - of frost, shadow, cloth, iron, sacking, straw and the stench not only of dung but of decaying human flesh. The players are forced to carry a friend's corpse on their cart for the first third of the book; truly, you long for his burial.

Out of the dark come shouts of colour: the beggar, fighting the "raw- boned" stray dog in the snow for a broken egg yolk; preparations for a jousting tournament in the castle yard; the chivalric hues and bleached sky beneath which the knights stretch their "silk-clad legs below the hem of their armoured skirts for the benefit of the ladies".

As for the play-acting itself, there's such an excitement in the writing - pure adrenalin on the page. Where else in fiction has the near- superhuman quality of drama, the scarily liberating power of the mask been so passionately and imaginatively explored?

The players are swept along in it until they are playing for themselves: without "any notion of where the play was tending, we were drowning in it, we had to snatch words from the air as drowning people snatch at breath." This is writing which makes you want to shout "I know!" with each keenly carved observation.

The melancholy truth of the book's last and most revealing line burns in your belly long after you've put it down - not that it's a book which you want to put down. I could have done with it being even longer - but maybe just a single extra word would have made it less eerily perfect.