'I call this place my laboratory,' he continued, 'though I have not yet found a suitable name for the science that I have been exploring here. This material will be of use to a mind trained in investigative procedures. If Herr Stiffeniis can work out how these crimes were perpetrated, he may antic.i.p.ate the murderer's modus operandi and apprehend him. Of one thing we may be absolutely certain. This person will kill again!'

'Totz had no idea how these people were murdered,' I admitted. 'But why should he have lied to me?'

Kant touched my sleeve lightly, as if to encourage me.

'Morik was killed for a political motive, Stiffeniis,' he said. 'Totz told you the truth in that respect, at least. He must have thought his conspiracy was about to be discovered. Hence, he murdered the one person who had direct knowledge of the facts, the one person he could not trust. Morik.'

'But why accuse himself of the other murders?'

Kant shrugged. 'Would you wish to appear in the pathetic guise of a ruthless murderer of defenceless children? Ulrich Totz may simply be trying to fashion a more attractive image for himself as a revolutionary, a pitiless local Robespierre. You'll have to force the truth from him.'

'I will!' I said, feeling a weight of anger building inside me.

Again, Professor Kant placed a restraining hand on my arm.

'Before you go,' he continued with great animation, 'there is something else for you to see. It was the pretext on which I invited you here. I am truly surprised that you have not asked about it already.'

Like a stage magician pulling a rabbit from a hat, he set a folded grey cloth down on the table. 'The Devil's claw! Its presumed existence inspires more fear in Konigsberg than any tangible fact could do. Uncover it, Stiffeniis.'

I held back.

'It won't bite,' he said with a brittle laugh.

The wrapping was thin. My nervous fingers felt a tiny form coc.o.o.ned within. Whatever it was, the object was small and weighed next to nothing. I unfolded the material on the table-top to reveal a tiny pointed fragment measuring less than two centimetres in length. It seemed to be made of ivory or bone.

'What is it, sir?' Koch whispered.

Kant shook his head before speaking. 'Part of the murder weapon. The tip, I presume. It was probably longer when the murderer jabbed it into the base of each victim's skull. Vigilantius found this fragment impaled in Jan Konnen's neck. We can a.s.sume that as the killer attempted to pull it out, the point snapped off.'

'In the night officers' report, the woman who found the body spoke of seeing the Devil's claw,' I noted. 'Obviously, she couldn't have seen this tiny piece. Does the discrepancy suggest that she actually saw the whole weapon sticking out of the dead man's neck?'

'It's a point worth investigating,' Kant suggested with a vigorous nod.

'I must speak to her. Lublinsky's reports are vague on this particular point.'

'Lublinsky might know where she is,' Koch added, picking up the fragment from the table and studying it with the sort of avid concentration a botanist might apply to an exotic fruit he had never seen before. 'If this one snapped and broke, the killer seems to have had no trouble obtaining a replacement, sir. I'd wager that they are easy to procure.'

'And to hide,' said Kant. 'No sensible man stands close to the butcher when he swings the cleaver in his hands.'

He turned to me, an amused glint in his eye.

'Do you see the way ahead now, Hanno?' he asked.

I looked at the gla.s.s jars, the files and the boxes stacked on their shelves.

'Everything here is new to me, sir,' I said with a shiver of excitement. 'But I promise to use these remarkable objects to the best of my ability.'

I might have been swearing a solemn oath.

'Here is the key,' said Kant with a kindly smile. 'The heads are there, the clothes the victims were wearing at the time are stored in those boxes. Each box is marked with the name. Sketches of the corpses are in those folders,' Kant pointed everything out with methodical calm, 'All you need, I believe, is in this room. The exhibits are yours, Stiffeniis. Use them as you think fit.'

Kant appeared to shrink before my eyes as he placed the key in my hand. I had the feeling that it had not been an entirely natural performance, though it had certainly been memorable. His nervous strength was utterly consumed.

'Take Professor Kant home in his coach, Koch,' I said. 'I will make my way on foot to the main gate. I want to speak to Lublinsky at once.'

'Oh no, sir. No!' Koch replied with force. 'You take the Professor home. I will return on foot to the main building of the Fortress. You'll get lost, sir, while I know precisely where to find Officer Lublinsky.'

'It could be dangerous,' I replied, puzzled by the fierceness of Koch's opposition to my proposal.

'I'll keep my wits about me,' the sergeant replied, glancing in the direction of Professor Kant. In a flash I realised what was troubling him. He was not afraid of the dark, the fog, or the unknown criminal stalking the night. He was frightened of Immanuel Kant.

'Very well,' I conceded. 'Find Lublinsky and see what he has to say about the woman, I will join you shortly at the Fortress.'

Outside, night had fallen. The fog was even denser than before, and cut visibility on the dark stretch of road beneath the Fortress to nothing. Johannes Odum leapt forward to open the door while I a.s.sisted Professor Kant to mount the carriage-steps.

'Will you be coming home with Professor Kant, sir?' Johannes asked, a note of caution in his voice. I suddenly recalled that the valet wished to show me something at the house.

'Of course, I will,' I replied, handing Professor Kant into the coach, and again I was moved by his frailty and the effort of will that it cost him to match the incredible energy of his mind.

'Be careful, Sergeant,' I warned, as I climbed up behind Professor Kant, and Koch slammed the door. 'Take no risks.'

The coach pulled away and proceeded slowly. Neither I, nor Professor Kant spoke for some time. At last, he turned to me. 'I hope you'll join me in a warming gla.s.s of Bischoff's cordial? It has been a tiring day, and we both need something strong to fortify our spirits.'

'With the greatest of pleasure, sir.'

The promise seemed to content him. A few moments later, he was snoring lightly, his head reclining against the seat. I leaned back myself, thinking of the letter I had intended to write to Helena announcing my success in hunting down the killer. Thanks to Professor Kant, my days in Konigsberg were not to be so quickly counted off.

Chapter 16.

Professor Kant slept all the way home. The driving energy that had sustained him throughout that day seemed to have left him utterly spent. Only minutes before, eyes sparkling with excitement, his movements had been swift, unburdened by age, his mind quick, speech animated. But slumped there beside me on the carriage seat, that glistening cape of his looked like an empty coc.o.o.n left behind by some recently hatched creature which had taken wing to find its way in the cruel world.

But I was not in the least tired. By an inexplicable law of osmosis, the energy that had left my mentor now pa.s.sed to me. That morning on the muddy banks of the River Pregel, I had seen the corpse of a boy, his head smashed beyond repair. I had just emerged from a sinister chamber of horrors which was barely conceivable in a howling nightmare. The streets of Konigsberg were dark and dangerous. A killer was lurking there, a ruthless being who thought nothing of taking human life, leaving tragedy in his wake, promising worse violence to come. But my heart was singing. I might have been returning from a walk through the idyllic woods of Westphalia. As we left Professor Kant's laboratory far behind us, my mind was filled with sensations that any other man might have reserved for a refined and precious collection of objets d'art. Was I disgusted by what I had seen in that dark and gloomy place? Quite the opposite!

I held the key to Kant's laboratory tightly in my hands, which shook with awe and fascination. Those exhibits were remarkable, but more remarkable was the fact that Kant had entrusted the custody of his collection to me. To me, and to no one else! It did not surprise me to learn that Herr Procurator Rhunken had not been privy to the secrets of the place. Poor, loyal Koch had been shocked by the news, but I was elated by it. Now I knew why Kant had chosen me instead of any other magistrate. Other men might be more experienced in the traditional ways of criminal detection, but Kant believed that I alone would be able to comprehend the utility of the exhibits and appreciate the macabre beauty there was no better word for it which his incredible mind had conceived and created in that place. Seven years before, Kant had advised me to become a magistrate. And now he was offering me the opportunity I had purposely sought to avoid in Lotingen. He had placed the material in my hands and invited me to prove that I was the first of a new breed of investigative magistrates, that I was capable of employing a totally revolutionary technique involving methods that had never been used before in the fight against the worst of all crimes. Crimes that could endanger the very peace of the Nation.

This was the reason that had impelled him to call Vigilantius, and use both his anatomical knowledge and his arcane skills to a.s.sist the law. Was there a magistrate alive who would have dared to employ such a stratagem? That was why he had wanted me to watch the necromancer at work the night before. Suddenly, I saw the doctor's skills in a wholly different light. Kant's aged mind was drifting towards some dark and final sh.o.r.e, but the great philosopher had not lost his grip on reality, nor his ability to apply logic and sound reasoning to the resolution of a conundrum. He was teaching me to do what he was physically no longer able to do for himself. He was my Socrates, he was leading me towards a completely new way of looking and doing. Investigating a criminal act was not simply a matter of gathering circ.u.mstantial information and worming the truth out of a reluctant witness, as Rhunken thought. As I had thought myself, I reflected, with a flash of honesty.

Kant had been preparing me for what I had just seen, training me to use such knowledge for the good of Mankind, warning me not to discount any evidence in the light of its perversity or monstrosity, as Sergeant Koch had called it. Surely, that was how Rhunken must have viewed Kant's way of doing things. As recently as the night before, I would have agreed with Rhunken. In a trice, I realised what I must do. When the case was over, when the murderer was caught and condemned, I would write a learned treatise of my own to celebrate the incomparable genius of Immanuel Kant. He had ventured further in this field than any other man before him, and I was thrilled by the prospect of learning from the inventor of this new procedure. I turned to watch the Professor sleep, my soul crushed by waves of emotion and grat.i.tude. I owed everything to him. He might have been my father. Indeed, I realised, I owed him more, far more, than I had ever owed my own father.

My head was spinning with the immensity of these considerations. I had to close my eyes to regain equilibrium, and did not open them again until the coach lurched suddenly and stopped. Outside, the fog was thicker than before. I glanced again to Professor Kant, but he slept blithely on. Beyond the window-gla.s.s, a face materialised in the milky darkness, and the ghostly apparition of Johannes Odum signalled me to step down into the road. I opened the carriage door with all haste and quiet.

'We can go no further, Herr Stiffeniis,' the valet announced as I stood beside him. The fog became an impenetrable wall at the point where a rippling stream ran beside the road. 'I'm very afraid of driving the coach into the ditch.'

'I'll walk ahead and lead the horse on,' I offered.

'Take one of the carriage-lamps, sir. Be careful, the way is treacherous here,' he advised.

I set off quickly in the direction of the house, but was forced to slow down. Beneath my feet the snow was tightly packed. Behind, the horse shied with fright. Johannes had him tightly reined in, fearing for the worst, but I was forced to plod on for an age before Professor Kant's residence finally loomed up out of the fog.

Johannes lifted Kant from the coach like a sleeping babe, while I held up the lamp and helped them by opening the door. Standing in the hall, I watched as the valet carried his master effortlessly up the stairs to his bedchamber, waiting there while Johannes made him good for the night. The operation took no more than ten minutes.

'He's truly worn out. Thank G.o.d for a moment's peace!' Odum whispered, as he reached the bottom of the stairs. 'But now, if you follow me, sir, I'll show you what I found this morning.'

Taking up the carriage-lamp, he opened the front door and led me with difficulty to the rear of the house. The kitchen garden was enclosed all around by tall trees. Snow lay in knee-deep drifts and folds, and the going was difficult.

'This is Professor Kant's private study,' he said, stopping by a darkened window. He lowered the lamp closer to the ground. 'But look here, sir. This is what scared me this morning.'

I looked down. The snow gleamed like diamonds in the beam of light. Dark imprints etched like stepping stones in the frozen mantle led all the way from the window to a wicket gate at the far end of the enclosure. I examined these vague footprints in the snow for a moment, wondering to myself what Johannes was so concerned about. Had the responsibility of looking after Professor Kant begun to wear on his nerves?

'Is this what you wished to show me?'

He glanced at the ground, then back to me. 'After we returned from the river this morning, sir, I opened the curtains in the study. And there they were!'

'I do not follow, Johannes.'

'No one's been out here since summer.'

I felt the muscles tense in my jaw. 'Are you certain? A neighbour, perhaps? A beggar, or a tradesman?'

Johannes shook his head with energy.

'There's only one possibility, sir,' he said with great seriousness. 'Some person has been spying on him. Or trying to enter the house.'

There was something lumbering, heavy almost stupid, I might say about the man. The cold air seemed to have dropped an appreciable number of degrees, and I shivered violently despite the heavy woollen cloak that Lotte Havaars had providently seen fit to pack for me.

'Or worse, Johannes,' I said with far more calm than I felt.

'Worse, sir?'

'The killer may have followed him here.'

'Oh, G.o.d!' Johannes exclaimed with a groan. 'I told Professor Kant he was becoming too involved in those murders. I warned you, sir. Being seen down there by the river was dangerous. Now, you must...'

I held up my hand to stop this flow of recrimination, concentrating on the measures which would need to be taken straight away. 'We will protect him,' I said. 'Make sure to bar the doors and lock all windows, Johannes. I will call the gendarmes to guard the house and watch the road.'

As I spoke, I stared at those footprints in the snow. What would Kant do in such circ.u.mstances as these, I asked myself. The answer came in a flash. My mind turned in the direction that Professor Kant had so carefully plotted out for it.

'There's something we must do first,' I said with decision. 'Herr Professor himself would have done it. Hold up that lamp, Johannes.'

'You'll not bring Professor Kant out here, I hope, sir?' Johannes cried with fright.

'What are you saying, man?' I replied. 'I would not dream of disturbing him. What I mean to do is apply the a.n.a.lytical method that Professor Kant has just been showing me in his laboratory.'

'Sir?' Confusion glistened in the servant's eyes.

'We need to find a specimen which is whole and compact,' I said, looking around me.

'A specimen? Of what, sir?'

'Of a footprint, Johannes. Keep that lamp close to the ground.'

The wind had made the top surface of the snow as brittle as gla.s.s. As I bent closer and studied the surface of the snow, I could see that some attempt had been made to cancel the prints. Whoever had been lurking outside that window had let his feet drag as he walked, to avoid leaving the very evidence that I was seeking.

'Follow the tracks across the garden,' I said.

Johannes mumbled some complaint or protest to himself, then held up the lamp and led the way.

'Do not step on the imprints,' I warned him. 'There's confusion here enough already.'

The tracks led to the hedge and a wicket gate in the far corner of the garden. They seemed to have been left by a person who was in a hurry, and they had all been distorted. Not one was whole. We pa.s.sed out into the lane at the rear of the house, but the footsteps of the pa.s.sers-by combined to render the task impossible.

'This is a hopeless task, sir!' Johannes burst out nervously.

I led him back to the garden in silence, examining the trodden area beneath the window once again, then moving on to the three stone steps which led up to the back door of the house.

'He's been here, you see? And here...'

A cry of triumph erupted from my lips. On the top step, springing into sharp relief as Johannes raised the flickering lamp, was the reward for all my stubborn persistence: a footprint in its entirety.

'He tried to enter by this door,' I said, beginning to search for drawing paper in my bag.

'D'you think he got inside, sir?' Johannes asked, a note of fear in his voice.

I carefully examined the solid barrier of dark pine and the large metal keyhole. Everything was neat, intact, untouched. 'There is no sign of an attempt to force it open. The door seems to be locked from inside,' I said, trying the handle.

'I barred it myself, sir.'

'He must have abandoned his plan. At least, for the moment,' I said, my voice catching in my throat. What would happen, I thought, if he found the way to break in next time? 'Come, Johannes, we must determine if this is the murderer's footprint.'

'But how, sir? How can you do that?' he said, an expression of blank incomprehension on the servant's face.

'By comparing this print with the tracings of footprints made where the murders took place,' I replied, realising even as I spoke that I was using the new investigative language of Kant, which could mean nothing to the servant. 'This is what your master would have done,' I explained. I had found a sheet of paper in my bag, and was searching in vain for a pencil. 'But what am I to draw with?' I murmured, looking around as if I expected a quill and a pot of ink to materialise before my eyes.

'Draw, sir? I don't understand you.'

'Those prints. I want to copy them. Is there a pencil in the house?'

'In my master's room, sir. But I wouldn't want to wake him.' He glanced around the garden. 'One moment,' he said, breaking a brittle twig from a leafless rosemary bush beside the kitchen door. He opened the lantern, burned the wood in the flame, extinguished the lighted stick in the snow, then handed it to me.

'Charcoal, of course!' I exclaimed with a smile.