I had turned my back to her and for a few calculated seconds glowered blindly through the window, past the shards of glass hanging precariously in their decrepit lead fittings. I cleared my throat softly and asked: 'And if I should refuse?'

'Then we both shall lose,' she replied evenly. 'Then my situation becomes most unfortunate.'

'There are other booksellers.'

'That's as may be. But none, I think, possesses your resources.'

That was true, or at least I liked to tell myself it was. But appeals to my vanity were no good. Nor was the appeal to my greed that followed.

'I shall pay you very well.' Her voice was coming from a few feet behind me, chiming with a note I'd not heard before. 'One hundred pounds. Will that be sufficient? Plus expenses, of course. I expect you will be required to travel.'

'Travel?' The idea appalled me. I had no wish to travel anywhere except back to Nonsuch House. A hundred pounds was a good deal of money, true enough. But what did I want with more money? I was perfectly happy as I was, with my handsome £150 a year; with my tobacco-pipe, my armchair, my books.

'One hundred pounds, mind you, simply to accept the task,' she was continuing. I could feel her eyes boring into my back. 'Then, should you find the book… as I am certain you will… one hundred more. Two hundred pounds, Mr. Inchbold'-she had adopted a tone whose levity belied the magnitude of the offer-'two hundred pounds simply to hunt down a book. My only condition is, of course, your complete discretion.'

Two hundred pounds for a book? Removing my spectacles I began polishing their lenses vigorously on the hem of my coat. My curiosity began to wriggle free from the strict tethers with which I had bound it. Two hundred pounds for a single book? Unheard of. Ridiculous. Half my entire stock could be had for that price. What sort of volume could possibly be worth such a sum? Even the Caxton binder's edition of St. Augustine's Confessiones-the edition I had glimpsed last night-could not possibly fetch a price as grand as that.

I replaced my spectacles and for a moment said nothing. Alethea had remained silent, awaiting my reply. Well… what did I really have to lose? It was possible I wouldn't be required to travel after all. I had all of my factors, of course: good men in Oxford, Paris, Amsterdam, Frankfurt. And Monk could be counted on to scour the bookstalls in Paternoster Row and Westminster Hall, or anywhere else I might see fit to send him. And for all I knew the book might even be on my walnut shelves at this very minute. Well? Stranger things did happen. After all, I knew for a fact that I had a copy on my shelves of Sir Walter Raleigh's Discoverie of the large, rich, and beautifull Empire of Guiana-a fifth title that I had made out on the upside-down page a minute earlier.

I turned round to face her. Almost despite myself I extended my hand.

'Well? What, may I ask, is the name of this valuable book?'

That afternoon I was slumped back in the seat of the carriage for the return journey to London. For the first time in hours-in days-I felt myself relax. Phineas cracked his whip, the horses plunged forward, the stunted trees flew past the quarter-lights. But then as we approached the archway we came within inches of colliding with a lone horseman riding full pelt towards the house.

'Sir Richard!'

'Bloody old fool! Out of my path!'

'Yes, Sir Richard!'

Phineas jerked the reins violently sideways. The carriage lurched towards the grassy verge, where the right front wheel jarred over a rock and then slipped into a trench. I was flung forward on to the floor of the box, twisting my hip. The rider spurred his mount, a big chestnut roan, and flew past my window with a rook-like caw.

By the time I righted myself we had climbed out of the trench and were passing beneath the archway. Grimacing, I twisted round in the seat and raised the leather flap on the tiny oval rear-window. I watched the rider dismount and then bow before Alethea, who curtsied and offered her hand. She had already changed into a riding-habit in expectation of his arrival. Her visitor was a big fellow in an old-fashioned millstone ruff and a high-crowned hat with a purple ribbon that twitched in the breeze. They were framed for a second by the wings of Pontifex Hall, two figures in an oil painting. Then we turned a corner and the painting was riven by a length of broken wall and unkempt hedgerow.

'Sir Richard Overstreet,' shouted Phineas, for once volunteering some information. 'A neighbour. Betrothed to marry Lady Marchamont.'

'Is that so?'

'Before the year is out, I shouldn't wonder. A scoundrel, sir, if you ask me,' he finished with uncharacteristic passion.

'Oh?'

But Phineas had said his piece. There were to be no further divulgations. We rode on, for three more days, in gloomy silence.

But the incident left a strange effect on me. My anger and impatience had drained away to be replaced by something else. For at some point during the previous day a small breach had been prised open. Certain images of Alethea filtered back along the irregular sluices of memory. As I closed my eyes these trickling channels carried past me images of her bent over the volumes, blowing dust from their bindings or tracing her fingertips across their surfaces like someone exploring the curve of a lover's face. Once she had even raised one of the books to her lips and, closing her eyes, sniffed at it as one would at a rose.

And so as the road twisted before us and untwisted behind I felt the first twinges of a confusing and unexpected distemper, the timid quivering of a stunted and vestigial organ for which, as with an appendix, I no longer had a use; something that, like a tail-bone or wisdom tooth, had been carried over from an extinct life, quiescent and forgotten. All at once I remembered how she looked at me in the crypt, as well as the dozens of books on sorcery crammed on to the shelves of the library, and for a moment I wondered if during my stay she might not have magicked me like a witch or a wisewoman-if some heathen spell was the source of these strange quavers. But before I could contemplate this foolish notion any longer, the leaky flood-hatches had been closed by the pain in my hip. Still, the event was no less worrying for its brevity. I would remain on the alert for further symptoms.

As my seat tipped back and forth I watched the combes open and dip, the hills and trees rise to meet us, then fall away. A few clouds hung overhead, grey as gun-smoke. Again I felt myself relax. Soon I would see the golden cupolas and brass weathercocks of Nonsuch House rising into the smoke-filled London sky. Soon I would be back inside my thick walls of books, sealed off from the alarming conundrums of the world. The events of the past day would seem nothing but a strange dream from which I had gratefully awakened, unsure of where I had travelled or what might have transpired.

But I would still possess a memento of my journey, a garbled testament of its strange purpose. As we reached Crampton Magna I withdrew a piece of paper from my pocket and stared hard at the smudged words inscribed in Alethea's old-fashioned secretary hand: Labyrinthus mundi, or The Labyrinth of the World.

Rattling about in my seat, I frowned at the paper as I had when Alethea first placed it into my hands. The name sounded vaguely familiar, though I was far from certain where I might have heard of it. It was the name of a work quite different from the other errant volumes, those treatises on navigation and remote explorations of the Spanish Americas. It was a parchment that dated, she claimed, from early in the fifteenth century, when it had been copied from a papyrus original-now lost-and translated into Latin by a scribe in Constantinople: a fragment of perhaps ten or twelve vellum leaves in the ornate oriental blind-tooled binding known as rebesque or arabesco. She would say nothing more except that it was a Hermetic text, an obscure one that had never been published. But how such a parchment could be worth two hundred pounds, and how it had become the mysterious index of Lady Marchamont's fortunes, such riddles I did not wish, at this point, to consider.