I passed the workshops and turned through a little gate into the lay cemetery. In daylight it seemed smaller. The headstones of locals who had paid for a place here, or visitors who had died within the walls, lay half-buried in the snow. There were three other large stone family tombs similar to the Fitzhugh crypt we had visited the night before. At the far end rows of fruit trees raised bare arms to the sky.

These crypts, I reflected, would make good hiding places. I ploughed my way towards the nearest, unhitching the abbot's key ring from my belt. I fumbled among the keys with cold, stiff fingers until I found one of the right size that fitted.

I tried each crypt in turn, but there was nothing hidden among the white marble tombs. The stone floors were dusty and there was no sign any of them had been visited for years. One belonged to a prominent Hastings family whose name I remembered as another ancient line wiped out in the civil wars. And yet those buried here would be remembered, I reflected, recalling the monks reciting their private Masses; remembered as names memorized and chanted to the empty air every day. I shook my head and turned back towards the orchard, where starveling crows cawed in the skeleton trees; I was glad of my staff as I stumbled among the gravestones.

A wicket gate led me into the orchard and I picked my way between the snow-laden trees. Everything was still and silent. Out here in the open, I felt that at last I had space to think.

It was strange to be inside a monastery again after so many years. When I was a pupil at Lichfield I had been a mere cripple-boy, of no account. Here I had the powers of a commissioner of Lord Cromwell, greater powers than any outsider had ever had over a religious house. Yet now as then I felt isolated, alone, disliked. The different element here was their fear of me, but I had to handle my authority carefully, for when men are frightened they close up like clams.

My talk with Brother Gabriel had depressed me. He lived in the past, a world of painted books, ancient chants, plaster statues. I guessed it was a world in which he sought refuge from continuing temptations. I recalled his anguished expression when I confronted him with his history. There were many I encountered in my career, blustering liars and deceitful rogues, whom I confess it was a pleasure to question, watching their faces fall and their eyes swivel as I unpicked some edifice of lies. But to harry unsavoury sins from a man like Brother Gabriel, who had a certain fragile dignity it was all too easy to undermine, that was no thing to enjoy. After all, I knew only too well what it was like to be a despised outsider.

I remembered how sometimes the taunts of the other children when I could not play their games had led me to plead with my father to take me away from the cathedral school and educate me at home. He had replied that if I was allowed to retreat from the world I would never rejoin it. He was a stern man, not given to sympathy and less so after my mother died when I was ten. Perhaps he was right, yet that morning I wondered whether I was better off if worldly success had led me to such a place as this. It seemed to do nothing but bring back bad memories.

I passed a row of dovecotes, beyond which a large pond surrounded by reeds could be seen. It was a stewpond, dug out for the keeping and breeding of fish. The little stream flowed into it before running through a small culvert under the rear wall a little way off. There was a heavy wooden gate nearby. Monasteries, I recalled, were always built by a stream to carry away waste. The early monks were clever plumbers; there was probably some arrangement to divert the waste to prevent it befouling the fish pond. I stood looking out over the scene, leaning on my staff, chiding myself for my gloomy thoughts. I was here to investigate a murder, not mewl over past sorrows.

I had made some progress, though not much. It seemed unlikely to me that this crime had been committed by an outsider. But although the five senior officials all had knowledge of Singleton's purpose, I could not see any of them becoming so overcome with wild hatred that they would kill him and place St Donatus's future in even greater danger. Yet they were all hard men to read, and about Gabriel at least there was something tormented and desperate.

I turned over the idea that Singleton had been killed because he had found something out about one of the monks. That seemed more likely, yet I could not square it with the dramatic manner of his murder. I sighed. I wondered if I would end by having to interview every monk and servant in the monastery, and my heart sank at the thought of how long that might take. The sooner I was away from this wretched pile and its dangers the happier I would be; and Lord Cromwell needed a solution. But as Mark had said, I could only do what was possible. I must plod on, as lawyers do. And next I must check whether outsiders could gain access from this marsh. 'All the circumstances,' I muttered as I ploughed on through the snow. 'All the circumstances.'

I reached the pond and looked in. It was covered with a thin skin of ice, but the sun was almost overhead now and I made out the dim shapes of large carp flickering through the reedy water.

As I straightened up something else caught my eye, a faint yellowish glint at the bottom. Puzzled, I leaned forward again. At first I could not locate what I had seen among the reeds and wondered whether it had been a trick of the light, but then I saw it again. I knelt down, my hands smarting at the touch of the snow, and peered in. There was something, a patch of yellow at the bottom. The casket was gold, and many expensive swords have gilt handles. It was worth investigating. I shivered. I did not fancy confronting those icy depths now, but I would come back later with Mark. I rose, brushed the snow from my clothes, then gathered my coat around me and headed for the gate.

I saw that in a couple of places the wall had crumbled and been patched up, crudely and unevenly. Unhooking the bunch of keys from my belt, I found one that fitted the heavy, ancient lock. The gate creaked open and I stepped out onto a narrow path. It ran alongside the wall, the land dropping away at the edge a final few inches to the marsh. I had not realized it came so close. In places the path was broken where the mire had advanced right up to the wall, undermining it so it had had to be rebuilt. It was even more crudely patched outside. In places an agile man could climb that uneven surface. 'Damn it to hell,' I muttered, for now I could not eliminate even that possibility.

I looked out over the marsh. Covered with snow, broken by thick clusters of reeds and frozen stagnant pools, it stretched for half a mile to the broad band of the river, the blue sky reflected in its unfrozen waters. Beyond the river the ground rose slowly again to a woodland horizon. Everything was still, a pair of seabirds on the river the only sign of life. As I watched they rose into the air, calling their sad cries to the cold heavens.

Halfway between the river and where I stood was a large knoll, an island in the marsh. It was topped with a jumble of low ruins. That must be the place Brother Gabriel had mentioned, where the monks had first settled. Curious, and holding my staff carefully, I set one foot down from the path. To my surprise, the ground under the snow was firm. I let down my other leg and took a step forward. Again I felt firm ground. But it was only a skin of frozen, matted grass, and suddenly my foot crunched through, squelching into miry softness. I let out a cry, dropping my staff. My leg was being sucked slowly into what felt like thick mud; I felt slime and icy water come over the top of my overshoe and trickle down my shin.