'And can you think of anyone who might have had his mind tempted to murder?' I asked quietly. 'Remember I speak with the authority of the vicar general, and through him the Supreme Head of the Church, the king.'

He looked me directly in the eye. 'I can think of no one in our community who might do such a thing. If I could, I would have informed the abbot. I told you, I believe an outsider was responsible.'

I nodded. 'But there has been talk of other grave sins here, has there not? The scandal under the last prior. And small sins may lead to larger ones.'

His face reddened. 'It is a large step from – those things – to what was done last week. And those acts were in the past.' He stood abruptly and moved to stand a few paces off.

I got up and stood beside him. His face was set and his brow had a sheen of sweat despite the cold.

'Not all in the past, Brother. The abbot tells me Simon Whelplay's penance was in part because of certain feelings he nurtured towards another monk. Yourself.'

He turned, suddenly animated. 'He is a child! I was not responsible for the sins he contemplated in his poor mind. I did not even know till he confessed to Prior Mortimus, or I would have put a stop to it. And yes, I have lain with other men, but I have confessed and repented and sinned no more in that way. There, Commissioner, you have plumbed my history. I know the vicar general's office loves such tales.'

'I seek only the truth. I would not trouble your soul merely for a pastime.'

He seemed about to say something more, then paused and took a deep breath. 'Do you wish to see the library now?'

'Yes, please.'

We returned down the nave. 'By the way,' I said after we had walked some distance in silence, 'I saw the great crack in the side of the church. That is indeed a large job. The prior will not approve the expenditure?'

'No. Brother Edwig says any programme of repairs must be limited to the revenues available each year. That will barely suffice to prevent the damage from spreading.'

'I see.' In that case, I thought, why were Brother Edwig and the abbot talking of needing capital from land sales?

'These men of accounts always believe that what is cheapest is best,' I continued philosophically, 'and prink and save till all falls about them.'

'Brother Edwig thinks saving money is a holy duty,' he said bitterly.

'Neither he nor the prior appear much given to charity.'

He gave me a sharp look, but said nothing more as he led me from the church.

Outside, my eyes watered in the cold white light. The sun was high now and gave brightness if not warmth. More paths had been cleared through the snow and people were going about their business again, black habits criss-crossing the white expanse.

The library building, next to the church, was surprisingly large. Light streamed in from high windows, illuminating shelves crammed with books. The desks were empty, save for a novice scratching his head over a heavy tome, and an old monk in a corner laboriously copying a manuscript.

'Not many at study,' I observed.

'The library is often empty,' Brother Gabriel said regretfully. 'If someone has to consult a book, he usually takes it to his cell.' He went over to the old monk. 'How are you progressing, Stephen?'

The old man squinted up at us. 'Slowly, Brother Gabriel.' I glanced at his work; he was copying an early bible, the letters and the painted figures beside the text worked in intricate detail, the colours standing out brightly on the thick parchment, only slightly faded after centuries. The monk's copy, though, was a poor affair, the letters scratchy and uneven, the colours gaudy. Brother Gabriel patted him on the shoulder. 'Nec aspera terrent, Brother,' he said, before turning to me. 'I will show you the illustration of Barabbas's hand.'

The sacrist led me up winding stairs to the upper floor. Here were more books, innumerable shelves stacked with ancient volumes. Thick dust lay everywhere.

'Our collection. Some of our books are copies of Greek and Roman works made in the days when copying was an art. Even fifty years ago those desks downstairs would have been filled with brothers copying books. But since printing came in no one wants illustrated works, they are happy with these cheap books with their ugly, square letters all squashed together.'

'Printed books may be less beautiful, but now God's word can be brought to all.'

'But can it be understood by all?' he replied with animation. 'And without illustration and art to stimulate our awe and reverence?' He took an old volume from the shelves and opened it, coughing amidst the dust it raised. Little painted creatures danced impishly among lines of Greek text.

'Reputedly a copy of Aristotle's lost work On Comedy,' he said. 'A fake, of course, thirteenth-century Italian, but beautiful nonetheless.' He closed it, turning to an enormous volume that shared a shelf with a number of rolled-up plans. He pulled them out and I took one to assist him. I was surprised when he grabbed it back.

'No! Don't take it!'

I raised my eyebrows. His face reddened.

'I am sorry – I – I would not have you get dust on your clothes, sir.'

'What are those?'

'Old plans of the monastery. The mason consults them sometimes.' He withdrew the volume beneath. It was so large he had difficulty in heaving it over to a desk. He turned the pages carefully.

'This is an illustrated history of the monastery's treasures, set down two hundred years ago.' I saw coloured pictures of the statues I had seen in the church, and other items like the lectern in the refectory, each drawing annotated with measurements and a Latin commentary. The centre pages were taken up with a coloured illustration of a large square casket set with jewels. Inside a glass panel, on a purple cushion, lay a piece of dark wood. A human hand was fixed there by a broad-headed nail driven through the palm; withered and ancient, every sinew and tendon visible. From the measurements the box was two feet square and a foot deep.

'So those are the emeralds,' I said. 'They are large. The casket could have been stolen for its precious jewels and gold?'

'Yes. Though any Christian doing such a thing would lose their immortal soul.'

'I always thought the thieves crucified with Christ had their hands tied to the cross rather than being nailed to it, so that their suffering should be prolonged. So it is shown in religious paintings.'

He sighed. 'No one really knows. The gospels say Our Lord died first, but he had been tortured beforehand.'

'The misleading power of paintings and statues,' I said. 'And there is a paradox here, is there not?'

'What do you mean, sir?'

'That hand belonged to a thief. Now his relic, which people paid to view until that was forbidden as usury, is itself stolen.'

'It may be a paradox,' Brother Gabriel replied quietly, 'but to us it is a tragedy.'

'Could one man carry it?'

'Two men bear it in the Easter procession. A strong man could carry it, perhaps, but not far.'

'To the marsh, perhaps?'

He nodded. 'Perhaps.'

'Then I think it is time I had a look out there, if you would show me the way.'

'Certainly. There is a gate in the rear wall.'

'Thank you, Brother Gabriel. Your library is fascinating.'

He led me back outside and pointed to the cemetery. 'Follow the path through there, past the orchard and the fish pond, and you will see the gate. The snow will be thick.'

'I have my overshoes. Well, no doubt we shall meet again at supper. You will be able to meet my young assistant again then.' I smiled disingenuously. The sacrist blushed and lowered his head.

'Ah – yes, indeed-'

'Well, Brother, I thank you for your help and your frankness. Good day.' I nodded and left him. When I glanced back he was walking slowly back towards the church, head bowed.