'Go on,' I urged him.

'Well, I thought at first it was Professor Kant, sir. He sometimes opens the window to change the air in the room. But then I heard, that is, I thought I heard something else.'

'Come to the point, Johannes!'

'Murmurs, sir. Voices. I jumped up and sc.r.a.ped my chair loudly on the flagstones. If some thief had broken in, I wanted him to know that Professor Kant was not defenceless and unguarded.'

'Had someone forced an entrance?'

'I knocked and ran into the study at once, but Professor Kant was alone. Then I heard a noise in the adjoining kitchen, and would have given chase, but...'

'But what, Johannes?'

His eyes opened wide and he stared at me for some moments. 'Professor Kant prevented me, sir.'

'He stopped you?'

'He was as pale as ash, holding his hand to his heart, clearly disturbed by whatever had happened. I couldn't leave him on his own, could I, sir? Not even to chase off the robbers. He was gasping for air as if about to suffocate. He was in a frightful tizzy!'

'He had seen the intruder, then?' Though shocked by the risk that Professor Kant had run, I was excited by the possibility that he might have seen the face of the murderer.

Johannes again shook his head. 'I don't think so, sir. I gave him a drop of brandy to calm him down, and the first thing he did was to thank me for waking him up.'

I looked at him with a frown. 'Forgive me, I don't follow you.'

'A nightmare, sir. He said he'd probably called out in his sleep. Well, I saw no point in alarming him further. If there had been any danger, it was past.'

'But you did hear a noise?' I asked.

He shook his head uncertainly. 'The kitchen door was open,' he blurted out. 'Either I had forgotten to lock it, or someone had let themselves out that way. But I'd swear I locked it from the inside, sir.'

'I am sure you did,' I rea.s.sured him. 'Did you call the soldiers?'

'First, I helped Professor Kant up to bed. I did not wish to frighten him even more. Then, I went to talk to the soldiers, but they had seen nothing, n.o.body. The fog last night was a real pea-souper.'

'How was your master this morning?' I asked.

Johannes looked down at his boots and mumbled, 'He seemed well enough, sir. I brought him tea in bed, and he smoked his usual pipe, but then he fell asleep again. I did not have the courage to open the curtains, sir. He's not himself this morning. He wanted the fire lit in his room, complaining of a chill which had risen to his head. And his bowels...'

'Tell him that I am here,' I said.

Johannes bowed and turned to go, but I placed my hand on his arm. What the servant had told me at the beginning came back in all of its importance.

'Wait a minute! He was working last night, you say?'

'So he told me, sir.'

'And what was he doing exactly?'

'He was writing, sir.'

'What was he writing?'

'I do not know.' The valet's eyes narrowed. 'And when I put away his implements this morning, there was no sign of the paper I'd set out for him last evening. Not a single page! His quills were worn, the inkpot dry, but whatever he'd been writing has disappeared...'

The study door opened with a creak and Professor Kant stepped out into the hallway. 'A most successful evacuation, Stiffeniis!' he exclaimed with a radiant smile. 'A finely formed stool, substantial in its density of faecal composition, and with a minimal liquid content. I hope that you have managed something of the sort yourself this morning?'

'Oh, decidedly, sir,' I managed to reply. The first time I had met him, he had spent a good half-hour discussing the workings of his bowels with his close friend, Reinhold Jachmann, over lunch. It was, apparently, a subject of which he never tired. 'Did you sleep well, Professor?'

'Never better, never better,' he replied dismissively.

And he did look to be in fine fettle. With the exception of two details. The first was his periwig. He must have donned it himself at the sound of visitors out in the hall. The ma.s.s of powdered curls sat uncomfortably far back on the crown of his head, his own silken hair, as fine and white as the gossamer threads of a spider's yarn, exposed beneath it. For the rest, as always, he was immaculately dressed in a padded three-quarter-length house-jacket, made of crushed satin the colour of Burgundy wine, brushed linen trousers reaching down to the knee, and pink silk stockings. The second anomaly, slightly ludicrous in the circ.u.mstances: he was still wearing his bedroom slippers. As a rule, Kant received guests as if, at any moment, he might be called to leave the house with them. He pointed down at his domestic footwear with an apologetic smile, and said, 'I was late in rising from my bed this morning.'

'I did not intend to disturb you, sir,' I apologised.

'Nor have you. I am sure you have much to tell me,' he replied, leading Koch and me into his study, where he took a seat in an upright wooden chair with wings. It was, I realised, a commode. Placing his elbow on the arm of the chair, he rested his head delicately on his upturned hand. There was a lingering smell of warm humanity in the room, and his nose twitched appreciatively. He looked like a silkworm wrapped up within a warm coc.o.o.n of his own making, though his ice-blue eyes were as sharp and wide awake as ever. Everything in his aspect seemed to deny the nocturnal drama that Johannes Odum had just narrated. For all his physical fragility, Kant appeared to be the very axis of a world that turned simply because he wished it to turn.

'Well?' he said.

'I have found the weapon used by the murderer, sir,' I began.

A lightning bolt of energy seemed to rocket around the room. Kant sat up straight in his chair. 'Have you really?' he said.

I drew the Devil's claw out of my pocket. Unfurling the filthy rag in which it had been kept by Anna Rostova, I held it up to his view.

'Goodness gracious me!' he exclaimed. I had hoped to impress him, and I was not disappointed. As he held out his hand to touch the object, I noticed that his fingers were trembling. 'What is it, Stiffeniis?'

'Sergeant Koch thinks it may be a knitting needle. It appears to be made of bone.'

'Would there not be an eye for the yarn in that case?' Kant asked, taking the needle in his hand and bending forward to study it more closely.

Koch had been silent, standing stiffly at my back all this while. 'It's been cut short, sir,' he said suddenly.

'Of course,' Kant nodded sagely. 'The murderer has fashioned a tool to meet his own precise requirements.'

'This needle was stolen from the body of Jan Konnen,' Koch went on, apparently warming to his tale. 'The piece that you found, sir, was the tip of this very item. It must have broken off as the murderer was trying to extract it from the corpse. We may deduce from this that the killer has a supply of them.'

'Equally, Herr Koch,' Kant responded sharply, as if he were annoyed by something the sergeant had said. 'we may deduce that there is a precise reason why he chose this peculiar object, and no other, for the task. Where did you find it, Stiffeniis?'

'A person I have been interrogating gave it to me,' I began to say, spinning my triumph out, but Kant was impatient for details.

'A person involved in the killings?'

I nodded. 'I believe so, Herr Professor, though I wish to be certain before I make another arrest. She...'

'She?' He looked up quickly. 'A woman?'

'Indeed, sir.'

'Are you a.s.suming that the owner is a woman because of the feminine nature of this object?' he asked, his eyes darting to the Devil's claw couched in the palm of his hand, as if it were a rare and precious b.u.t.terfly he feared might fly away.

'That's why I came, sir. I needed to confirm my line of reasoning with you.'

Kant turned to me with a grimace of mad irritation on his face.

'Do you persist in believing that Logic can explain what is going on in Konigsberg?' he snapped.

I blinked and swallowed hard. The oddity of the remark did not escape me. Professor Kant had spent his entire life defining the physical and moral worlds of Man by means of Logic alone. Did he now deny that vital principle?

'I see that I've disconcerted you,' he continued with a conciliatory smile. 'Very well, then, let us summarise the uncomfortable position in which we now find ourselves and see where your Logic leads us. The killer a woman, if your suspicions are correct has chosen a most unusual weapon. It is not a gun, or a sword, or a knife. Nothing that we would recognise as a weapon, but something ba.n.a.l and apparently innocuous. And with this domestic instrument, this woman has brought the city of Konigsberg to its knees. Am I correct?'

He paused and looked at me. 'My first question, Stiffeniis. What can be her purpose?'

'There's reason to believe that witchcraft is the cause, Herr Professor.'

'Witchcraft?' Kant p.r.o.nounced the word as if it were an insult addressed personally to him. He shook his head, and his face became a mask of malevolent sarcasm which, for a moment, shocked and entranced me. 'I thought you said just now that you had come here to be guided by Reason?' he went on with merciless irony.

I struggled to compose a reply. 'The woman describes herself as a familiar of the Devil, sir,' I said, attempting to justify my position. 'Witchcraft may well be a motivation for the murders, but I have no conclusive proof as yet that she is actually the killer.'

'So you still presume that there are rational motivations in this case,' he continued. 'My second question. Do you think that witchcraft will supply them for you? Not so very long ago, you believed that a terrorist plot was the cause.'

'That was my mistake,' I admitted. 'I don't deny it, sir. For that reason, I wish to make sure of her guilt before I arrest her. "We must bring light where the darkness reigns..." '

'How I detest being quoted!' he interrupted in a tone that was very near to rage. 'You have faced the turmoil which dwells within the human soul. You know it is a more powerful driving force than any other. Perhaps you ought to consider its role in this specific case.'

He leaned towards me, his musty breath invading my nostrils, throat and lungs, like a sour, suffocating wind. 'Once before, I seem to recall, you found yourself in similar uncharted territory, and what you saw there frightened you. You told me yourself, you had no idea that such pa.s.sions could exist. Well, they do! You know your way through this labyrinth. That is why I sent for you. I thought that you would be able to put your own experience to good use.'

Against my will, I stiffened.

'Don't take it ill, my young friend,' he continued with a complicit smile. 'I a.s.sembled the evidence in that laboratory for someone with an open mind, a man who would be able to use it, and reach conclusions which are not so unthinkable as they appear. But come, tell me why you suspect a woman of the murders.'

I spoke of Anna Rostova with relief, describing the steps that had led me to her. I was careful not to mention the footprints that Johannes had found in the garden the day before. Nor did I tell him that although I had sent the soldiers out to search for Anna Rostova, I hoped never to see or hear of her again.

'So, this instrument has truly done the Devil's work,' said Kant with gravity when I had finished. 'The woman may, or may not, have committed the murders with this needle, but she has certainly put out Lublinsky's eye. I'm sorry to have been the cause of his involvement in this case. He's seen his share of ill fortune.' Kant shook his head. 'Lublinsky served me faithfully, or so I believed. But the money I paid him for those sketches came second to the desire to cure his good looks. And where did this lead him? He was an ugly brute before. He'll be uglier now. Goodness gracious!'

I listened in silence to this monologue, but I was not blind to what I could see, nor deaf to what I could hear. Kant showed no sense of pity for the man, no real sorrow for having involved Lublinsky in an affair that had pushed him into an abyss from which there was no coming back. There was no compa.s.sion in the Professor's voice. Nor in his eyes, which sparkled greedily over that instrument which lay exposed in the palm of his hand.

'It is about those drawings that I have come, sir,' I said, interrupting the silence that had fallen. 'Concerning the kneeling position in which the victims were found. You pointed out that missing detail when we examined Morik's body. I must apologise for my blind stupidity. Of course, I had seen the position of Herr Tifferch's corpse, but I only recognised its significance when I saw the sequence of drawings in your laboratory. As I understand it, the a.s.sa.s.sin induced the victims to kneel down before striking them. This is the mystery within the mystery. How do you think it was done, sir?'

'I hoped that you would find an explanation,' Kant said with a shrug. 'I have not been able to resolve this enigma. Nor could Doctor Vigilantius provide any clue, whether anatomical or paranormal,' he added thoughtfully, raising his hands to cover his eyes as if to isolate himself by excluding the sight of everything and everyone around him. He remained in silence for an unconscionable time. Then, suddenly, he looked up at me and a smile spread over his face like the sun coming up to illuminate the dark Earth. 'Do you recall the first thing I said to you about the weapon when we went to examine the jars in my laboratory?'

Could I ever forget those words? I inscribed them on the very first page of this testimonial. ' "It went in like a hot knife cutting lard," ' I recited.

'Precisely,' Kant confirmed. He held the Devil's claw close to his right eye, which was less clouded by cataracts than the left, and peered at it. 'The ease with which this needle could be handled was the reason it was chosen. It requires no physical strength, no undue manipulative skill. The only thing needed is a little knowledge of anatomy. Knowing the most vulnerable point to enter the seat of the brain, the cerebellum. This is the key to its efficacy. And yet, it is not so easy to deliver the death-blow as it may seem.'

'What do you mean, sir?'

'The victim may not cooperate,' Kant replied with a mincing smile.

'They offered themselves up to be murdered?' I asked. 'Is that what you are suggesting, sir?'

Kant did not reply.

'It sounds like the Devil's own way of going about the business to me,' I heard Koch murmur dubiously, though I paid him no attention. Instead, I recalled a phrase that Doctor Vigilantius had spoken in the name of Jeronimous Tifferch: 'When asked, I felt no fear...'

What had Tifferch been asked to do? Had the necromancer sensed something vital concerning the modus operandi of the murderer?

'It was all done in a fraction of a second,' Kant said in a whisper. 'Before the victim realised what was happening, it was too late. The chosen one had to be immobilised. He, or she, had to acquiesce in some way. But how? If the needle struck an inch to the left or to the right, there was the risk of failure. The killer certainly foresaw this possibility. He or she must have thought long and hard about the danger before finding an answer.'

'An expedient that would prevent the victim from moving,' I murmured. 'Some stratagem that would convince the prey to pause long enough for the killer to strike. The murderer induced Paula-Anne Brunner to lift up her gown and kneel in the wet mud in her stockings.' Mounting excitement almost overwhelmed me. 'Why did she do so? Because...because the face we are convinced is hideous and evil was familiar to her. She did not feel threatened. "The Devil's is a face, no more," Tifferch said through Vigilantius.'

'A face like any other,' Kant added with conviction.

'She could have been obliged to kneel at pistol point,' Koch objected.

'Why not shoot her, then?' Kant's hand dismissed the suggestion with a quick flight through the air. 'No, no, Sergeant. The use of one weapon to compel obedience, and another to ensure death, defies common sense. There was no sign of a struggle, no testimony that cries for help were heard. The deed was done quickly. And there was compliance in it.'

'A weapon that excludes the need for strength, the use of a stratagem to distract and immobilise the victim, a face with nothing exceptional or frightening about it.' I listed the evidence. 'All this suggests that the psychological need to kill is greater than the killer's physical capacity to commit the crime. Cunning is used in the place of physical force. May we deduce that the murderer is unable to act in any other manner?'

Kant looked at me for a moment, and his thin lips drew back in a smile.

'A person who is weak? Is this what you are theorising, Stiffeniis?'

I nodded.

'What sort of person has no alternative to strength?' Kant continued. 'A person who is frail by congenital nature. A person sick or infirm. A woman. An old man...Is that what you're suggesting, Stiffeniis?'

Was he trying to steer me towards Anna Rostova?

'Many elements point to this woman,' I said.

'You mentioned witchcraft,' Kant reminded me.

'I need to verify it, sir.'

'It is a start, Stiffeniis. At least we now know that the terrorism theory was a red herring.'

So, there it was. I had convinced him. Kant had sneered at the notion of witchcraft, but I had brought him round. I had his blessing for the new line of investigation that I was about to take. Just then, the doorbell tinkled loudly, and Johannes entered the room a moment later.

'Herr Stiffeniis, there is a man outside to speak with you,' he announced.

In the hall, a young gendarme was vigorously rubbing and blowing on his large hands, which were blue with cold. I knew what he was about to say before he opened his mouth, though I have always refused to believe in presentiments. Such coincidences are part of the general incoherence of Life, not emanations of the hidden design of G.o.d, or any other Supreme Being. Even so, it was a strange sensation.

'Anna Rostova?' I asked, the blood pumping quickly in my veins as he stepped forward and told me what I both wished and feared to hear.

'Yes, Herr Procurator. She's been found.'