The house in Klopstra.s.se stood out from its brightly coloured neighbours like a rotten tooth. The once-green paint was peeling and grey. A dead ivy vine grasped the facade like a skeletal hand intent on throttling the life out of the building. A rusty balcony running the length of the upper floor seemed likely to collapse with the next winter storm. The shutters, half-closed and broken, hung sadly from their hinges. It was not a pretty sight. Herr Reinhold Jachmann's days of gracious and fashionable living seemed to be long past.

'Shall I go in with you, sir?' Koch asked.

'No, Sergeant,' I said quickly. I wanted no witness to the conversation I was about to have. 'Go to the Court House, and see about that list of aliens I mentioned. Send the gendarmes out to check it.'

Koch bowed stiffly. Was it my impression, or did a look of disappointment flash across his face? I watched him march away with all the haste that the fresh-fallen snow would permit, then I turned towards the house. The wrought-iron gate protested loudly when I pushed to open it. A loud shriek gave way to a long painful groan as I forced back rusty hinges which had not tasted whale-oil in many a month. Apart from the crusted footprints that Koch himself had left there earlier that morning as he came to deliver my message, no other impression had been made in the snow. No visitor or tradesman had called before or since.

I let the iron knocker fall against the door, and the sound seemed to echo and rebound on the icy air as if the house and garden were enclosed within a vacuum. A lone blackbird flew away, twittering angrily. That sudden noise shattered the silence which reigned supreme in the garden. The motionless shrubs and bushes hidden beneath the deep coverlet of snow might have been forgotten tombstones in an abandoned graveyard. I was looking around forlornly as the door opened silently at my back.

'You have come then, Stiffeniis.'

I recognised the deep, resonating boom of Reinhold Jachmann's voice, though I did not recognise the man as I turned to face him. A cold, unearthly winter had blown over him, too. His thin hair was as white as bleached bed linen, his eyebrows large snowdrifts above piercing, coal-black eyes. His stiff seriousness alarmed me. I remembered a warm friendly man during our first and only meeting seven years before, but the suspicious stranger glaring down at me from the top of the steps was the very opposite. For one moment, I thought he would refuse to allow me to enter his house. We stared at each other in silence.

'This way,' he said at last, and led me through the hall and into a spa.r.s.ely furnished sitting room on the ground floor. Pointing to a sofa before a cast-iron fireplace where a single log smoked and smouldered, he asked me to be seated. It was more an order than an invitation. He watched me sit without a word, then he walked to the window and looked out over the garden.

'What brings you here?' he enquired without turning around.

'A matter of the greatest urgency, Herr Jachmann,' I replied. 'A Royal commission.'

'So you mentioned in your note,' he said. 'Can I know its nature?'

I had hoped he would not need to ask.

'I have been appointed to investigate the recent spate of murders in the town,' I said quietly.

With a sudden movement, he turned to look at me, some of his former energy returning. 'You, Stiffeniis? Investigating murder?'

He appeared to be stunned by what I had just told him. 'I thought that Procurator Rhunken was in charge of the case?' he said.

'He died, Herr Jachmann.'

He shook his head and looked confused. 'I have heard nothing of his death, nor of his burial.'

'It happened just yesterday evening,' I explained. 'Herr Rhunken was buried immediately. There was no funeral. It was his final wish.'

'Gracious me! What has become of Konigsberg?' he whispered, turning again to the window. He remained there for quite some time, peering out at the snow.

'I warned you, I told you, never to come here again,' he growled over his shoulder, his face livid with anger, as if I had brought these new disasters along with me from Lotingen.

Another brooding silence followed his outburst.

'I was very surprised to be a.s.signed the case,' I ventured to say at last. 'I accepted the commission with trepidation, sir. For the sake of...'

'Have you seen him yet?' Jachmann interrupted gruffly, his eyes still fixed on the garden and the street.

'Oh no, sir,' I replied. 'I would never dream of doing so without consulting you.' I paused for a moment, then blurted out, 'Your letter came as a great shock to me, Herr Jachmann. I have not gone back on my word, sir. His peace of mind is as precious to me as it is to yourself. I've not forgotten your warning.'

He turned to face me. 'But you intend to visit him now, do you not?' His voice had risen again, the blood rushed to his cheeks, and he stared at me with evident distaste.

I shifted uncomfortably in my seat. 'Not if I can help it,' I said, 'though there is the possibility that we might meet by accident. I thought I ought to warn you, sir. That is why I am here.' I stopped for some moments, but then curiosity got the better of me. 'How is he, sir?' I dared to ask.

'He is well enough,' Jachmann returned brusquely. 'His valet reports to me on a regular weekly basis.'

'His servant?' Now it was my turn to be surprised.

'His servant,' he confirmed sharply without adding anything more.

'But you are his closest friend, Herr Jachmann...'

'I was his closest friend,' he interrupted, his voice cracked, broken. 'I am still his domestic administrator, but I have not seen him in the past twelve months, or more. He has become secretive, almost a recluse. I go to his house no longer. All essential communication pa.s.ses through his valet.'

'How can this be, sir?'

He waved his hand dismissively. 'There was no quarrel, no argument, if that is what you mean. The professor has no time for old friends. His door is closed to all and sundry. His servant is instructed to say that he is busy, and does not wish to be disturbed. Work and study, as you know, have always been the mainsprings of his existence.'

He twirled away and paced up and down the room in silence, then came to rest once more in front of the sofa. He bent close, the deep lines of age in his long face etching themselves even more sharply with the effort to control his emotions or his temper.

'Why would any responsible person want you to conduct this investigation, Stiffeniis?' he enquired.

I know what I would have liked to reply. That the King had recognised my qualities, knowing that I would succeed where all other investigators, including Procurator Rhunken, had failed. But I was obliged to concede the truth.

'I do not know, Herr Jachmann.'

'I expected an angry reply to that harsh letter of mine,' he said suddenly. 'I knew that you would return to Konigsberg unless I managed to stop you. Had you answered telling me to mind my own affairs, or asking me to explain the motives that obliged me to write to you in such a manner, I would not have been in the least surprised. But when your answer came, stating meekly that you would comply with my wishes, I was more than surprised, I can tell you. I was alarmed.'

'I took you at your word,' I began to say, but he was not listening.

'You knew why I did not wish to see you ever again,' he continued angrily. He paused, drew a deep breath, then added: 'I have tried many a time to fathom what pa.s.sed between you both that day in the fog.'

I stared into his accusing eyes and held my breath, recalling the day seven years before when I had been privileged to speak in private with the most famous man in Konigsberg, Jachmann's friend and colleague at the University, Professor of Philosophy, Immanuel Kant.

'You ordered me to avoid the city for the good of Professor Kant,' I whispered. 'I had no idea why, but I saw no reason to question your integrity. You were his dearest friend. You knew what was good or bad for him, and...'

'You were bad for him!' His white face suddenly blazed with resentment. 'That is the point. Don't you see? Why should there have been any need for me to forbid you to see Kant? What other reason could there be to make me fear for the mental stability of the most rational man on Earth?'

'You are unjust, sir,' I protested, but Jachmann rode over me.

'I realised that something was amiss whenever your name was mentioned afterwards,' he continued with great intensity. 'It had such a marked effect on him. There was agitation in his manner, wild distraction in his eyes. It was out of character, totally unlike him. This madness began the day that he invited you to lunch. In itself, that was an event without precedent.'

'Why do you say so, sir?' I asked.

'He had never invited a stranger to his home before. Not once!' He looked at me inquisitively. 'Something in you triggered his interest. Something that you had done, or something that you had said to him.'

'But you know why he invited me,' I replied with pa.s.sion. 'I had just come back from Paris, Professor Kant was interested in what I had seen there.'

Jachmann nodded grimly.

'I recall your speech about what you saw the day the Jacobins executed their legitimate ruler...'

I closed my eyes to block out the memory. Would the image of that moment never leave me in peace? How long would it haunt me? The sight of human blood on the ground. The stench of it in the air.

'...Paris, January 2nd, 1793,' Herr Jachmann intoned pedantically.

The scene flashed before my mind's eye. The bubbling gaiety of the crowd. The condemned man in his soiled finery proudly climbing the steps to the block. The oiled blue triangle of steel shimmering in the early morning light. The sound of grating metal as the blade fell. Then, blood! Oceans of crimson blood, spurting out of that severed neck like water from one of the ornamental fountains that the King had built for himself at Versailles, drenching the faces of the onlookers. Falling like rain on my own face, on my mouth and my tongue...

'They murdered the King that day.'

A king? A man had been butchered before my eyes. A flick of a lever, and a shadow had been cast upon my soul. A hidden part of myself had risen up with the mob and taken possession of my confused mind.

'Kant had met others who had been in France,' Herr Jachmann continued. 'Others who were involved in those tragic events. He was not upset by what they had to say. But you, Stiffeniis! You brought a malignant plague to his house that day.'

He stared fixedly at me.

'Whatever happened between the two of you, Stiffeniis, it changed him. It changed him totally. And it all began with that conversation about the effect of electrical storms on human behaviour.'

'It was not I who raised the subject,' I spluttered in my own defence. 'You started it, sir.'

'But it was you,' Jachmann replied, his finger pointing accusingly, 'you, Stiffeniis, who led the discussion in such an unsavoury direction. You froze the blood in my veins!'

He turned his gaze to the fire. 'How many times have I regretted that odious conversation! Kant was studying the effects of electricity on the nervous system in that period, he was interested in little else. And the night before, there had been a terrible storm.'

Every single detail was still vivid in my mind.

'Looking out of your window,' I murmured, 'you found a stranger in your garden. Careless of the lashing rain, the thunder and lightning, he was staring up at the sky in a trance. You'd been disconcerted by his behaviour, and you asked Kant if static electricity might provide an explanation for it.'

'And he replied by saying it was not the electrical discharge, it was the unbounded energy of Nature which had fascinated the man,' Jachmann went on. 'The destructive power of the elements had mesmerised him. Kant referred to the incantamento horribilis. Human Kind, he said, is fatally attracted by Sublime Terror.'

He sat down heavily in an armchair, his forehead couched in his hand. 'I was shocked. Unable to believe my ears. Immanuel Kant? The Father of Rationality celebrating the powers of the Unknown? The dark side of the human soul?'

'I remember, sir. You objected that such power belongs to G.o.d alone. That Man is bound by moral ties which he should never question...'

'Then you spoke up,' Jachmann interposed, still shading his eyes, avoiding my sight, 'and suddenly the pleasant young student who had won our respect with his good manners and his sound reasoning appeared in a different light.'

'I just said...'

He held up his hand for silence. 'Your words are indelibly printed on my memory. "There is one human experience which may be equal to the unbridled power of Nature," you said. "The most diabolical of all. Cold-blooded murder. Murder without a motive." '

Jachmann stared at me, his eyes narrowed and resentful. I felt as if my body had been stripped away, my soul exposed to view.

'When Professor Kant shifted the discussion elsewhere,' he went on, 'I felt grateful to him. But the ghost that you evoked that day had not been laid to rest. He insisted on taking a turn around the Castle Walk alone with you, though he had not been out of doors all winter, except to go to the university. The fog was dreadful, you remember. But I knew that he would wish to talk with you again.'

'You are curious to know if we talked further of the same subject. Are you not?' I asked, on the defensive.

'You are wrong, Stiffeniis,' he replied. 'Totally wrong! I do not wish to know what was said. But let me tell you what happened as a consequence. When Kant returned to the house, I was waiting for him. Long before I saw him through the fog, I heard his footsteps. And what I heard was enough to convince me that something was wrong. Very wrong. Kant was running. Running! But from whom? From what? I rushed out to meet him, and the expression on his face was frightful to behold. Rather, I was frightened by what I saw. His eyes sparkled with nervous energy. I thought he had taken a fever. I expressed my concern, but he announced that he had work to do which could not wait an instant. In short, he sent me about my business! And the very next day, he told me that he had begun to compose a new philosophical treatise.'

I frowned. 'I have not heard of any new book,' I said.

Jachmann shook his head dismissively. 'It has not been published. That is why you've never heard of it. No one has read a single line. Indeed, I am inclined to believe that the work does not exist. At that time, he was under great mental strain. Some younger philosophers accused him of ignoring the deeper resources of the soul. Emotion, they suggested, was more powerful than Logic, and Kant was ruined by the bitter controversy. His cla.s.ses were empty in the last years of his tenure. The young did not want to pay to listen to him.'

'So I heard,' I said.

'It was very sad. He was all but forgotten. "Old-fashioned" is the new-fangled term, I believe. Things had got to such a state that one of his former proteges, a bright young fellow named Fichte you've heard of him, I'm sure described Kant as the "philosopher of spiritual idleness" in a book which sold very well throughout Europe.'

'That must have been humiliating.'

'Remember his legendary timekeeping?' Jachmann reminisced. He seemed calmer as he recalled the distant past. 'How the people in Konigsberg used to set their clocks by Kant's coming and going? Well, the new generation of students thought it such a clever joke to interrupt his lessons, coming in one after another, watch in hand, saying, "Late, sir? Me, sir? Your timepiece must have stopped, sir." It drove Kant to a premature retirement.'

'I can imagine his distress.'

'I doubt it!' Jachmann snapped. He was rambling now with the frantic energy of an old man for a lost cause. 'But the person who was most distressed was Martin Lampe.'

'His valet?' I asked in surprise.

'I had to dismiss him. After thirty years of faithful service! He'd been the perfect servant. Mental order and discipline may produce fine thoughts, but they do not make for the efficient running of a household. Kant has trouble putting on his own stockings! Lampe looked after him, while the master concentrated on his books.'

'So why did you send him away?'

'For Kant's own good, Stiffeniis!' He looked at me intently, as if searching for the correct tone of voice with which to say what followed. 'I no longer trusted Lampe. More to the point, I was afraid of him.'

'Afraid, sir? What do you mean?'

'Strange ideas had found their way into Lampe's mind,' Herr Jachmann went on. 'He had begun to behave as if he were Professor Kant. Why, he told me once that there would be no Kantian philosophy if not for him! The new book on which Kant was working, he claimed, was his, not his master's. When the students started deserting Kant's lessons, it was Lampe who had the most violent reactions. He became quite vehement, shouting, saying that Kant must show the world what he could do.'

'He had to go,' I agreed. 'But who is looking after the Professor now?'

Jachmann cleared his throat noisily. 'A young man named Johannes Odum manages the house and he seems to be doing it well enough.'

He fell silent. Indeed, there seemed to be little left to say, and I stood up, reaching for my hat, preparing to take my leave, having said what I had come to say.

'Why in the name of heaven did you choose the law of all subjects?' he asked me quietly.

I paused before replying. I ought to have been insulted, I suppose, but there was a measure of satisfaction in what I was about to tell him. 'That day I came to Konigsberg, Professor Kant himself advised me to become a magistrate.'

'Did he really?' Jachmann frowned, evidently puzzled. 'Given the wild opinions you expressed, I can only wonder at the soundness of his judgement!'

'It was during our walk around the Fortress after lunch,' I hurried on, ignoring the sarcastic jibe.

Herr Jachmann shook his head sadly. 'That walk! Everything seems to have started out there in the...'

There was a sharp rap at the door, and a man in dowdy brown serving-livery poked his head inside without stepping into the room.

'That person's here again, sir,' he announced, surprise writ large on his face, as if his master were unused to receiving visitors, and my own visit had been more than enough for one morning. 'To speak with Procurator Stiffeniis, he says.'

Koch was waiting out in the hallway, his face ash-white, his expression drawn and tense. 'I'm sorry to disturb you, sir, but it's a question of necessity.'

'What is it?'