He answered my gaze. 'I shall pray for that lad to be admitted to heaven in God's time. Sinner as he was.'

I turned away, peering through the snowflakes to where Goodhaps was tottering along; Mark had given him his arm. I wondered if he would make it to the town, make his escape.

In the infirmary hall Alice was still tending the old dying monk. He was conscious again and she was gently spooning gruel into his mouth. Attending to the ancient her face had a new softness, a gentleness. I asked her to accompany us to the infirmarian's little kitchen. I left them all there while I fetched the book the bursar had given me. They all looked at me expectantly as I held it up.

'According to the bursar, this is the book poor Singleton obtained just before he died. Now, Dr Goodhaps, and Alice Fewterer, I want you both to look at it and say whether you have seen it before. You will notice it has a large stain of red wine on the cover. It occurred to me in church that those who had seen the book should remember that stain.'

Goodhaps reached across and took the account book, turning it over in his hands. 'I remember the commissioner reading a book with a blue cover. It might have been this. I don't know, I don't remember.'

'With your pardon.' Alice leaned across and took the book. She studied the cover, turned it over, then said decisively, 'This is not the book.'

My heart quickened. 'You are sure?'

'The book Brother Edwig handed the commissioner had no stain on it. I would have remarked it; the bursar likes everything so clean and tidy.'

'Would you swear to that in a court of law?'

'I would, sir.' She spoke quietly and seriously.

'So now I can be sure the bursar played me false.' I nodded slowly. 'Very well. Alice, I thank you again. All of you, keep this quiet.'

'I will not be here,' Goodhaps said smugly.

I looked from the window; the snow had stopped. 'Yes, Dr Goodhaps, I think you should be on your way. Mark, perhaps you could aid the doctor on his road to town?'

The old man cheered up. 'Thank you, sir. An arm to lean on would be welcome, and I have my bags at the abbot's house. My horse is here, if it could be returned to London when the weather allows…'

'Yes, yes. But, Mark, make as much haste as you can. We have things to do when you return.'

He helped the old man to his feet. 'Goodbye, Commissioner,' Goodhaps said. 'I hope you keep safe in this pestiferous place.' And with that cheerful valediction, he left us. I returned to my room, secreting the book under the bedclothes. I felt pleased. This was progress. I wanted to investigate the church and the pond next, and wondered how long it would take Mark to get to Scarnsea and back; on his own, little over an hour, but with the old man – I chid myself for a soft noddle, but I had not liked to think of Goodhaps stumbling through the drifts with his bags.

I decided to visit the horses; they had not been out for several days. I went back outside and made my way over to the stables. There a stable boy, sweeping up, assured me the animals were in good condition. Indeed both Chancery and Mark's Redshanks looked well, and were pleased to see me after so long inside. I stroked Chancery's long white head.

'Would you be out, old horse?' I said softly. 'Better to be bored in here than adrift in that place outside. There are worse things than standing in a stall.'

The stable boy passed, giving me an odd look.

'Do you not talk to your horses?' I asked him. He muttered something unintelligible and returned to his sweeping.

I said goodbye to the animals and walked slowly back to the infirmary. In the courtyard I saw that a space had been cleared in the snow. Squares of different sizes had been chalked on the exposed ground and half a dozen monks were playing a game that involved making intricate steps on the throw of a dice. Bugge stood watching, leaning on his spade. At the sight of me the monks paused and made to step aside, but I waved them to continue. I recognized the game from Lichfield, an elaborate combination of hopscotch and dice that was played in all the Benedictine houses.

As I stood watching, Brother Septimus, the fat foolish monk whom Brother Guy had chid for over-eating, limped by, puffing and blowing as he waddled through the snow.

'Come and join us, Septimus,' one of the monks called. The others laughed.

'Oh no – no I couldn't, I would fall.'

'Come, we're playing the easy version. No trouble even for a noddle like you to follow.'

'Oh no-no.'

One of the monks grasped his arm and led him protesting into the middle of the cleared area, the monk already there moving aside. They were all grinning, even Bugge. Almost at once, though, Septimus slipped on a patch of ice and went over, landing on his back with a howl. The other monks roared with laughter.

'Help me up,' Brother Septimus howled.

'He's like a woodlouse on its back! Come, woodlouse, up with you!'

'Give him some snowballs!' one called. 'That'll raise him!'

The monks began throwing snowballs at the poor creature, who between his weight and infirmity found it impossible to rise. He cried out as snowballs burst all over him, twisting and rolling so that he looked more like a stranded tortoise than ever.

'Stop!' he yelled. 'Brothers, I pray you, desist!'

They went on pelting and catcalling. This was no good-natured jest such as I had witnessed the night before. I was considering whether to intervene when a loud voice cut through the noise.

'Brethren! Stop that now!'

The monks dropped their snowballs as the tall figure of Brother Gabriel strode up, frowning angrily.

'Is this Christian brotherhood? You should be ashamed of yourselves! Help him up!' Two of the younger monks hastily aided the puffing, gasping Septimus to his feet.

'To the church! All of you! Prime is in ten minutes!' The sacrist started a little as he noticed me among the watchers. He came over to me as the brothers dispersed.

'I am sorry, Commissioner. Sometimes monks can be like naughty schoolboys.'

'So I see.' I recalled my conversation with Brother Guy. 'No Christian brotherhood in that performance.' I looked at Gabriel anew, realizing he was not a senior official for nothing; he was more than capable of exercising authority and moral force when necessary. Then as I watched the power seemed to drain from his face and it was overcome with sadness.

'It seems a universal rule in this world that people will always look for victims and scapegoats, does it not? Especially at times of difficulty and tension. As I said earlier, sir, even monks are not immune to the Devil's wiles.' He gave a brief bow and followed his brethren into the church.

I resumed my way to the infirmary, passing again through the hall to the inner corridor. I felt hungry and paused at the kitchen to take an apple from the bowl there. As I did so something outside caught my eye. A great splash of scarlet across the white snow. I crossed to the window. Then my legs almost gave way.

Alice was lying face down in the garden, a broken pot at her side. She lay in a lake of blood that even now spread steaming across the snow.