I followed Barak to the kitchen, trying to pull myself together. A middle-aged man sat at the table. He was plump and respectable looking, which no doubt was why Beak knap had chosen him. He rose to his feet and gave a deep bow. 'Master Shardlake, sir, a pleasure to meet you. Adam Leman, sir.'

I sat down opposite him, while Barak stood looking on.

'Well, Master Leman, I hear my brother in the law, Stephen Bealknap, has employed you as a compurgator.'

Leman nodded. 'I have assisted him.'

'To swear to the good character of men held in the bishop's gaol under benefit of clergy.'

He hesitated. I noticed his eyes were watery, and his nose a mess of broken red veins. A drunk, probably unable to run his stall properly and in need of extra cash for strong beer.

'Master Bealknap is kind enough to pay me a retainer,' he said cautiously. 'Perhaps I do not know all the gentlemen whose character I swear to as well as I might, but I feel I am doing a Christian service, sir. The conditions in the bishop's gaol-'

I cut through his nonsense. 'You pretend to know people you have never heard of and pervert the course of justice for money. We both know that. Now, have a beer.' I nodded at Barak, who fetched a jug from the cold cupboard. Leman coughed, then sat up in his chair.

'Bealknap hasn't paid me, sir. I said I'd do no more work for him till he did. He's the meanest man alive, he'd skin a flea for its hide and tallow. Makes a point of never paying anyone if he can get out of it.' He nodded self-righteously. 'Well, now it's caught up with the bastard. I've told your man I'll help you nail him and I shall. Thank you.' He took a cup from Barak and gulped noisily. 'That's good in this hot weather.' He looked at me sharply. 'You can give me immunity?'

I ever preferred a rogue who would come to the point. I nodded. 'In exchange for an affidavit to go before the disciplinary authorities of Lincoln's Inn. But once we've completed the affidavit I want you to come with me and tell Bealknap to his face what damage you can do him. Will you do that?'

He hesitated. 'How much?'

'A pound for the affidavit, another for coming to see Bealknap.'

'Then it'll be a job I'll be happy to do, sir.' His looked at me curiously. 'You got some grudge against him yourself?'

'You mind your business,' Barak said.

I rose. 'Come then, Master Leman, let us go to my study and prepare this affidavit.'

I spent an hour with the rogue. He signed the document with a scrawled flourish and I sent him on his way with five shillings on account for his fee. As I rubbed sand over the florid signature to dry it Barak laughed.

'I've never seen an affidavit taken before. The way you kept him to the point.'

'It's an art you learn. Now I am hungry. I'll get Joan to make us an early supper.'

'And then – the well?' Barak looked at me. 'We may not get another chance.'

For myself, now the business with Leman was done, the horror of the day's earlier events was crowding back into my mind and the expedition to Sir Edwin's house in the dark was the last thing I wished for. But it had to be done.

'Yes, the well. We'll have to wait till it's dark.' I glanced at the satchel, which I had retrieved from the cloister of St Michael's before returning home, and slung in a corner. 'I'll take the chance to look at those books.'

I RETURNED TO MY STUDY after a quick supper. I read for hours, lighting candles as the summer sun dropped to the horizon and the moon came up with the thick, hot darkness. As ever, reading soothed my mind and took me far away from my troubles. I read about Roman experiments with fire weaponry that seemed to come to naught. The name Medea came up again and again; the name of the ancient Greek sorceress who presented her enemy with a shirt that burst into all-consuming fire when it was put on. Placing 'the Shirt of Medea' on victims in the arena was a sport in Nero's time, mentioned in Plutarch and Lucullus. But what was it that made the shirt burn, and why had the Romans not developed this 'infernal fire' for military use?

I read on, finding references to military experiments with a mysterious substance called 'naphtha' that was found in Mesopotamia, on the eastern frontier of the empire. Pliny said it bubbled to the surface from underground and could be set on fire even if it spilled into a river. So God had seeded something in the earth there, as he seeded gold or iron in different places. I knew alchemists were able to locate deposits of some desired substance, such as iron or coal, by studying the nature of the ground, though they had never found deposits of the fabled 'philosopher's stone' that could turn base metals into gold, however often they might gull poor fools into believing they had.

I laid down my book and rubbed my eyes. I must see Guy, I thought. Barak would not like me telling Guy more, so I would have to keep the visit from him. This world of the discovery and transformation of matter was alien to me, yet there was something in these books, some clue, I was sure. Or why had the Lincoln's Inn copies been stolen? Who had stolen those books? Who was it the old librarian was afraid of? I sighed. Every step I took seemed only to throw up more puzzles.

I jumped at a knock on the door. Barak stood there, dressed in black doublet and hose, suppressed excitement in his eyes. 'Ready?' he asked. 'It's time to go to Sir Edwin's.'

WE WALKED DOWN TO Temple Stairs to catch a boat. Barak carried a heavy knapsack that he told me contained tools to break the locks on the well cap, candles and a rope ladder to climb down. It felt strange to be out on illicit business at night; if a constable asked to see the contents of that knapsack we would be in trouble. Barak, though, seemed quite unconcerned, nodding and smiling at the occasional watchman who lifted his lamp as we passed.

We took the path through Temple Inn, silent and dark save for the occasional flicker of candles at a window. We passed the great round bulk of Temple church, where the crusading Knights Templar had worshipped.

'Those were the fellows, eh?' Barak said. 'The Christian powers were on the march in those days, not forever being beaten by the heathen Turks like now.'

'Christendom was united then.'

'Maybe it will be again if we get Greek Fire. Under us. King Henry's navies burning the French and Spanish navies off the seas. We could cross the Atlantic and take the Spanish colonies.'

'Don't get carried away.' I gave him a cold look. The way he talked of burning navies repelled me. Had he not seen the burnings at Smithfield? Seen what fire did to men? 'Perhaps it would be better if it never came to pass.'

He inclined his head, but did not reply. A moment later he bent down and picked up some of the pebbles that separated the rose-filled flower beds from the path, putting them in his pocket.

'What are you doing?'

'These might come in useful,' he said ambiguously.

The Thames came into view, broad and shining in the moonlight, the lamps on the boats pinpricks on the water. 'We're in luck,' I said. 'There's a wherry at the stairs.'

THE MOONLIT RIVER was quiet, only a few boats carrying officials between the City and Westminster. I sat looking at the faint lights on the Southwark shore, thinking of Chancery again. Well, he was gone, gone to nothing for animals have no souls, but that was better than hell, where most men must have their end, perhaps me too for all I knew. I realized that when I was attacked I had thought only of survival, my mind sharpened by danger, I had not thought to pray or of what might happen after if I was killed. Was that sinful? I shook my head; I was exhausted, but I had to stay awake and sharp.