'Someone else killed? Jesu. This skein gets more tangled by the hour.'

'I know. And we have little time to untangle it. Come.'

We went down the corridor to Brother Guy's infirmary. He was at his desk, squinting at his Arabic book.

'Ah, you are awake,' he said in his soft accent. He closed the text reluctantly and led us to a little room, where more herbs hung from hooks. Inviting us to sit at the table, he set bread and cheese and a jug of weak beer before us.

'How is your patient?' I asked as we ate.

'A little easier this morning, thank God. The fever has broken and he is in a deep sleep. The abbot is coming to visit him later.'

'Tell me, what is Novice Whelplay's history?'

'He is the son of a small farmer towards Tonbridge. Brother Guy smiled sadly. 'He is one of those too soft by nature for this harsh world, too easily bruised. Such souls often gravitate here, I think it is where God intends them to be.'

'A soft refuge from the world, then?'

'Those like Brother Simon serve God and the world with their prayers. Is that not better for all than the life of mockery and ill-treatment such people often have outside? And in the circumstances he could hardly be said to have found a refuge.'

I looked at him seriously. 'No, he found mockery and ill-treatment here too. When we have eaten, Brother Guy, I would like you to take me to the kitchen where you found the body. I fear we have had a late start.'

'Of course. But I should not leave my patients for too long-'

'Half an hour should be enough.' I took a last swig of beer and rose, wrapping my cloak around me. 'Master Poer will stay here in the infirmary this morning, I have allowed him a morning's rest. After you, Brother.'

We went through the hall, where Alice was again attending to the old monk. He was as ancient as any man I had ever seen, and lay breathing slowly and with effort. He could not have been a greater contrast to his plump neighbour, who sat up in bed playing a card game. The blind patient was asleep in a chair.

The infirmarian opened the front door, stepping back as nearly a foot of snow banked up against the door fell over the threshold.

'We should have overshoes,' he said, 'or we shall get foot-rot walking in this.' He excused himself and left me looking out, my breath steaming before me. Under a blue sky the air was as still and cold as any I remember. The snow was that light, fluffy sort that comes in the hardest weather, the devil to walk through. I had brought my staff, for with my poor balance I could easily go over. Brother Guy returned carrying stout leather overshoes.

'I must have these issued to the monks with outside duties,' he said. We laced them up and stepped up to our calves in the snow, Brother Guy's features standing out darker than ever against the whiteness. The door to the kitchens was only a short distance away, and I saw the main building had a common wall with the infirmary. I asked if there was a connecting door.

'There was a passage,' he said. 'It was closed off at the time of the Black Death, to minimize the spread of infection, and has never been reopened. A sensible measure.'

'Last night when I saw that boy I feared he had the sweating sickness. I have seen it, it is terrible. But of course it is produced by the foul airs of the towns.'

'Mercifully I have seen little plague. Mostly I have to deal with the consequences of too much standing at prayer in a cold church. And of old age, of course.'

'You have another patient there who seems poorly. The ancient.'

'Yes. Brother Francis. He is ninety-four. So old he is become a child again and now he has an ague. I think he may be near the end of his pilgrimage at last.'

'What is wrong with the fat fellow?'

'Varicose ulcers like Brother Septimus, but worse. I have drained them, and now he is enjoying some rest.' He smiled gently. 'I may have a task getting him up again. People do not like to leave the infirmary. Brother Andrew has become a fixture, his blindness came on him late and he fears to go outside. His confidence has gone.'

'Have you many old monks under your care?'

'A dozen. The brothers tend to be long-lived. I have four past eighty.'

'They have not the strains or hardships of most people.'

'Or perhaps their devotions strengthen the body as well as the soul. But here we are.'

He led me through a stout oak door. As he had described the night before, a short passage led into the kitchen itself. The door was open and I heard voices and the clattering of plates. A rich smell of baking drifted out as we proceeded up the passage. Inside, half a dozen servants were preparing a meal. The kitchen was large, and seemed clean and well organized.

'So, Brother, when you came in that night, where was the body?'

The infirmarian paced out a few steps, the servants watching curiously.

'Just here, by the big table. The body lay on its front, legs pointing to the door. The head had come to rest there.' He pointed to an iron vat marked 'Butter'. I followed his gaze, as did the servants. One crossed himself.

'So he had just come through the door when he was struck,' I mused. There was a big cupboard by the spot where he had fallen; the assailant could have hidden at the side and then, when Singleton passed, leaped out and struck him down. I paced out the steps and swung my staff in the air, making a servant jump back in alarm. 'Yes, there's room for a big swing. I'd guess that's how it was done.'

'With a sharp blade and a strong hand, yes, you could do it,' Brother Guy said pensively.

'If you were skilled, used to swinging a large sword about.' I looked around the servants. 'Who is head cook here?'

A bearded man in a stained apron stepped forward, bowing. 'Ralph Spenlay, sir.'

'You are in charge here, Master Spenlay, and you have a key to the kitchens?'

'Yes, Commissioner.'

'And the door to the courtyard is the only way in and out?'

'It is.'

'Is the door to the kitchen itself locked?'

'No need. The courtyard door is the only way in.'

'Who else has keys?'

'The infirmarian, sir, and the abbot and prior. And Master Bugge the watchman, of course, for his night patrols. No one else. I live in; I open up in the morning and close at night. If anyone wants a key they come to me. People will steal the viands, you see. No matter that it's for the monks' table. Why, I've seen Brother Gabriel hanging about the corridor some mornings, looking as though he was waiting for our backs to be turned before snatching something. And he an official-'

'What happens if you are ill, or away, when someone wants access?'

'They'd have to ask Master Bugge or the prior.' He smiled. 'Not that people like to bother either, if they don't have to.'

'Thank you, Master Spenlay, that is very helpful.' I reached out and took a little custard from a bowl. The cook looked put out.

'Very nice. I will trouble you no further, Brother Guy. I will see the bursar next, if you could point me to his counting house.'

He gave me directions and I plodded off, the snow creaking under my overshoes. The precinct was much quieter today, people and dogs keeping indoors. The more I thought, the more I considered only an expert swordsman would have had the confidence to step out behind Singleton and strike off his head. I could not imagine any of the people I had seen managing it. The abbot was a big man, and so was Brother Gabriel, but swordsmanship was a craft for gentlemen, not monks. Thinking of Gabriel, I remembered the cook's words. They puzzled me; the sacrist had not struck me as the kind of man to hang around a kitchen to steal food.

I looked around the snowy courtyard. The road to London would be impassable now; it was not pleasant to reflect that Mark and I were more or less trapped here, with a murderer. I realized that unconsciously I had been walking in the centre of the courtyard, as far as possible from shadowy doorways. I shivered. It was strange walking alone through this white silence under the high walls and it was with a sense of relief that I saw Bugge by the gate, shovelling a path through the snow with the help of another servant.