Rather than trust to the hospitality of that plague-ridden city, I happily made camp beside the road and waited until the next morning to proceed any farther – and anyway, the gates were already closed for the night.

At dawn the gates opened and people emerged, bringing the plague victims with them: some they carried, some they dragged. I resumed the saddle and as I drew near, the odour of the place reached me – a foul stench of sickness, rot, and death that made the gorge rise in my throat.

I swallowed hard, crossed myself, and rode on.

A pall of smoke rose from a great refuse heap to hang like a filthy rag over the camp, and I saw what appeared to be bundles of cast-off clothes scattered in their hundreds all around. Closer, I discovered that these were not bundles, but bodies. I tethered the horses on a patch of withered grass a short distance away and approached on foot, picking my way carefully among the Yellow Ravager's victims.

There were so many! Everywhere I looked, I saw more, and still more. I believe the numbers shocked me more than the sight and smell, which were both appalling. I gazed in dismay at the scattered bodies of men, women, and children – in their hundreds, mind, and more being brought out through the gates -many, if not most, to be dumped beside the road like so much refuse, discarded and forgotten. Those who had given up the fight lay still and silent; but those in whom life yet warred cried in their torment, moaning and mewing as they twitched and writhed.

The groans of these unfortunates filled the air with a low, queasy keen. Their faces were spotted and distorted, their eyes red, their sores pus-filled and running; they vomited and defecated and bled over themselves, and lay rotting in their own filth. I had not witnessed the devastation of the Yellow Ravager before, yet judging by what I saw around me, I knew it was well named: the poor wretches mewing and crying in their throes were uniformly cast in a lurid shade of yellow – as if their flesh had been tinted by noxious dye and wrung out while wet – their skin was bloated, and vile mucus ran from nose and eyes to choke them; they sweated and panted as if being consumed from within by fire.

Many reached out their hands to me, crying for help, for release, but I could do nothing for them.

I knew the plague had worsened in the south; I had heard the bleak tidings like everyone else, but had no idea it was this bad. If it did not end soon, I reckoned, there would be no one left in Londinium to even bury the victims, let alone care for them. Oppression hung over the camp like the nasty smoke from the smutty little fires that had been lit here and there to burn the plague sufferers' clothing. This served to heighten the feeling of gloom and foreboding and misery into a sensation so palpable that I could almost see Death hovering over the camp, black wings outspread, gliding slow.

I also saw scores of monks at work among the plague victims, for the church had shouldered the burden of caring for the diseased and dying. These stalwart clerics carried water to the fevered and warm cloaks to the shivering; they prayed with the distressed and comforted the dying. And though they strove valiantly against an insidiously powerful adversary, their struggle was in vain. There were far too few of them to sway the course of battle. The cause, so far as I could see, was lost – yet they fought on.

The good brothers had used the rubble stone of the fallen wall behind them to erect hundreds of small enclosures over which cloth and skins were placed to form hovels in which the more curable of the sick might lie. Need had far outstripped the monks' kindly provision, however, and they had begun laying the plague-struck toe-to-toe, rank upon rank in endless rows beneath the crumbling wall. Meanwhile, the busy brothers hastened among the sprawled bodies on urgent errands.

I caught one brown-robed cleric and asked of him where I might find Brother Paulus. The monk pointed to a tent beside the wall, not far from the gate, and I made directly for the place. Once, when stepping over a body of one I thought a corpse, I felt a hand reach out and snatch hold of my foot. A pitiful voice cried, 'Please!'

Revulsion swept over me. I jerked my foot free.

'Please…' the wretch moaned again. 'I thirst… I thirst.'

Ashamed of my harsh reaction, I glanced around to see where I might find some water to give the poor fellow, and saw a monk carrying two flasks. I ran to the brother, told him I had need of the jar, and returned to the man on the ground, then knelt beside him, put my hand beneath his head, and raised him up a little to drink. His hair was wet and his skin damp and cold; his rheumy eyes fluttered in his head when I put the jar to his lips. I watched in horror as a black tongue darted out to lap at the water.

'Bless you,' he whispered, his breath sighing out between his teeth.

'Drink,' I urged. 'Take a little more.'

It was only after entreating him a second time that I realized I was clutching a corpse. I put aside the jar, lowered his head to the ground, and stood, wiping my hands on the ground. Hardening my heart, I walked on, ignoring the pleas of those I passed. God help me, I walked on, lest through their defiling touch I should become like them.

What if Arthur is right, I thought, and the most Holy Grail can end this suffering? What if it could bring about the miracle Arthur believes? Then he must try. Anyone with half a heart would try. Indeed, the king would have to be either a coldhearted fiend or insane not to attempt anything that held out even the slightest hope for healing his people. Certainly, a king of Arthur's stamp must do everything in his power to bring this healing about.

These things I thought, and began, at last, to understand Arthur's obsession with the shrine. I regretted my doubt and mistrust, and repented of my disbelief. Who was I, an ignorant warrior, to question the things of God? Thus, as I walked along, I found myself praying: Great Light, let Arthur be right. Hasten the completion of the shrine, and let the Grail do its work. Let the Grail do its saving work, Merciful Lord, and let the healing begin.

I reached the tent and ducked gratefully inside, where I found Paulus hunched over a low table, pouring his healing potion from a large jar into smaller vessels for distribution to the afflicted. 'Brother Paulus,' I said, and he looked up, recognized me, and smiled. It was the tired, forlorn smile of an exhausted man. His hair was lank and his eyes were sunken; his flesh had the wan, pallid look of a person too long confined.

'God be praised, it is Gwalchavad!' he said, genuinely pleased to see me. 'Greetings!' He took two steps towards me, then caught himself. 'You should not be here,' he warned. 'Tell me quickly what you have to say, and then leave.'

Taking him at his word, I said, 'Greetings, Paulus. I bring supplies and provisions from your fellow monks. I also bring word that Lady Chads is required at the Tor. The Pendragon has sent me to fetch her. If you will tell me where she may be found, trust that we will depart as soon as the horses are unburdened.'

That would be best,' the haggard monk agreed, replacing the jar and drawing his sleeve across his damp forehead. 'Come, I will show you.'

'Please, I would not disturb you. Just tell me where she is, and I will find her myself.'

The dutiful monk waved aside my offer. 'It will be quicker to show you,' he insisted.

He led me out along the wall, passing the burning refuse heap on the way – where I saw to my horror that it was in fact an immense pit which had been dug in the earth, filled with logs, and set alight to burn the dead. By twos and threes the corpses were thrown onto the sputtering heap. The smoke stank and the corpses sizzled. Down in the lower depths of the pit, black, grinning skulls nestled among the red embers. I turned my face, held my breath, and hurried by.