I halted, unable to continue.

Kant's grip tightened on my sleeve. 'You ask yourself where you have failed. Is that it? You wonder what is the obvious fact that you have overlooked.'

'I do, sir. You have provided all the instruments necessary to comprehend what is happening here in Konigsberg. Yet I have failed miserably. Can you still believe that I am capable of solving these murders?'

Kant did not reply immediately. He laid his hand on mine. His dry flesh settled gently on my own like dust. It was meant to be a comforting gesture, and I could not fail to respond to it. Then, he leaned closer, whispering into my ear.

'When you came to me this morning,' he said, 'with the murder weapon and a new theory about a witch, I admit it, I doubted whether I had done the right thing in naming you to run this investigation. I thought that it might be better to...free you from the tiresome burden I had placed upon you.'

'You did, sir?' I asked, the breath escaping from my body like the last wheeze of a punctured bellows. This judgement was the final blow to what was left of my pride and my faith in myself.

He sighed aloud. 'But I have changed my mind. That's why I came,' he said. 'My time on earth is short. In spite of your mistakes, you must continue what you have begun.'

'But I have failed you, sir! Ever since...'

He did not let me finish.

'You know something that the likes of Rhunken could never imagine,' he said with relish. 'I prepared the evidence in my laboratory for a rational man who would understand the logic of cause and effect. A leads to B, B to C, and nowhere else, of course. But this is only one side of the coin. There is another vital aspect to consider in these murders. The most important of all.'

'What is it, sir?' I asked, clasping my hands in a gesture of impotence. 'What can there be that you have not already indicated to me?'

'The bent wood of the human soul, Hanno. Logic has no place in human affairs. Have you forgotten what you came to tell me the first day that we met?' He did not wait for me to respond. 'I have never forgotten your words for one instant. I referred back to that first colloquy of ours when we were standing together over the body of that boy on the banks of the River Pregel the other day. Sergeant Koch that perceptive man expressed his surprise when I proposed the idea. He must have thought me quite a monster. But you ignored the suggestion, and now you persist in your obstinacy. You have known the answer for longer than you care to admit. "There is one human experience equal to the unbridled power of Nature," you said. "The most diabolical of them all. Cold-blooded murder. Murder without a motive." You remember saying that, don't you?'

His eyes searched mine. Then, he patted my arm again.

'You should take account of it, strange and horrible as it may sound. You are closer to the truth than you think,' he encouraged with a blinding smile. 'And this morning you told me about the mud stains on the victims' clothes.'

I frowned uncomfortably, while Kant sat back, his eyes narrowed. 'The killer induces his victims to kneel before he strikes them. We agreed on that, did we not?'

'And I a.s.sumed that a woman might be responsible.'

'But the killer was not a woman,' he said with a spurt of energy. 'This stratagem tells us much about the kind of person that the killer is.'

'You have formed an idea, Professor?' I asked eagerly, but Kant held up a finger to silence me, then laid it on his forehead as if to indicate the notion that was taking shape in his head.

'This person's desire to kill is greater than his ability to carry out the deed. He chose that weapon for its precision and the minimal effort its use required. Do you recall what I said when I showed you the severed heads and the incision at the base of the victim's skull?'

' "It went in like a hot knife cutting lard," ' I quoted.

'Precisely! But how did the killer induce the victims to stay still?'

'Lublinsky,' I murmured to myself.

Kant stared at me as if he thought I were mad. 'What about him?'

'I spoke with him an hour ago, sir. He told me something which would seem to support your argument. He said that each of the victims was holding an object clasped in their hand when they died. He did not mention the fact in his reports to his superiors. Nor to you, I imagine.'

'You see?' Kant exclaimed vigorously, his eyes shining brightly with excitement. 'Such purposeful cunning! Lublinsky is "bent wood" of the first order. But let us put the pieces of this mosaic together. First, the victims do not shy away from the person who approaches them. Second, they kneel down voluntarily before him. Third, they hold an object in their hands. Then they die. You prefer the path of Logic, Hanno,' he said with an ironic smile. 'Tell me, what do you deduce from these elements?'

Before I could reply, he continued in the same didactic tone: 'The killer asked for help. He appealed to human kindness, inviting the chosen one to pick up some small object that he had dropped on purpose as a bait. Of course, they all complied. That is human nature. And as they knelt, each one exposed the nape of his neck to the fatal dart. There, I've told you what I came to say. Now, I'll leave you to your task.'

In attempting to stand up, he succeeded only in sc.r.a.ping the bench on the stone floor as I jumped up to a.s.sist him.

'You must promise me one thing, sir,' I said.

'I never make promises,' he replied with a bewitching smile, 'until I know precisely what they involve.'

'Very well,' I laughed, my care and confusion set aside by his show of fresh confidence in me. 'In the future, if you have anything to tell me, send for me, and I will come to you.'

I did not finish the sentence. In that instant, the door flew open and a cold draught swept through the room as a soldier came bursting in. Johannes trailed behind, a worried look written on his pale round face.

'I hope you have good reason to enter in this rude manner?' I snapped.

The guardsman stepped forward and removed his black leather kepi.

'News, sir,' he said with a brisk salute, and my thoughts turned to Koch immediately. Had he sent another message?

'Body found in Sturtenstra.s.se fifteen minutes ago,' the soldier announced. He glanced hesitantly at Professor Kant, then back to me. 'I left the rest of the squad behind, and ran down here. Herr Stadtschen told me to run across an' tell you direct, Herr Procurator.'

'You were patrolling the area?'

'Marketplace to the town hall, sir. Up an' down. Every thirty minutes, sir, reg'lar as clockwork. Cathedral bell struck three. Daylight fading...'

Immanuel Kant's voice fractured the soldier's report.

'Behold, Darkness will cover the Earth!' he intoned with solemnity.

I turned to look at him in the half-light, and a smile seemed to flash across his face as he completed the citation like a clever child displaying his knowledge of the Holy Scriptures: 'Isaiah, Chapter 60, Verses 2 and 3'.

Chapter 27.

Before my arrival in the city, the gendarmes had been instructed to report every instance of violent death to Procurator Rhunken. Having stepped into Herr Rhunken's shoes, so to speak, I was now directly responsible for the action to be taken in any such case. The fact that there was a cold-blooded murderer abroad in Konigsberg did not simultaneously put an end to domestic squabbling or other crimes which might end in loss of life. I did not automatically attribute every new death to the chain of killings that I was investigating, therefore. Indeed, from what the messenger had told me, there were many reasons to induce me to think otherwise.

The timing of the murder was an important factor in my chain of reasoning. With the single exception of Paula-Anne Brunner, whose time of death had never been precisely ascertained, all the other victims had been killed at night, and I had no reason to expect such a dramatic change of modus operandi in my quarry. This latest corpse had been discovered as the clock was striking three, which suggested that the person had died during the hours of daylight. Next, there was the question of where the body had been found. Even I, who knew so little of the urban geography of Konigsberg, realised that Sturtenstra.s.se was a busy street leading down to the fish market. The other murders had been committed in out-of-the-way places again, with the exception of Paula-Anne Brunner, who had been killed in the deserted Public Gardens. Would the murderer I was chasing have taken the unwarranted risk of being seen and identified in Sturtenstra.s.se?

'Have you any idea who the victim is?' I asked, turning to the soldier. 'Or what may have caused the death?'

He shook his head. 'It's a man, sir, but we didn't go near the body. Our orders are to touch nothing if we chance upon a corpse.'

I turned away, satisfied.

'You pa.s.s near Sturtenstra.s.se on your way home, do you not, Johannes?'

'Indeed, sir,' he replied.

'With your permission,' I said to Professor Kant, 'I'll ride along with you in the coach. Johannes may set me down near my destination.'

Kant did not reply, though he did accept my supporting arm as we left the room. But outside in the courtyard, something very odd happened. As I was helping him into the coach, he grasped my sleeve and pulled me so close that the point of his hat struck me square in the centre of my forehead.

'Don't you understand?' he hissed in a sibilant whisper. 'I...I am losing control.'

'Control, sir?' I asked, disconcerted by his words. 'What do you mean?'

But he had lapsed into a graveyard silence. Johannes jumped aboard with a heavy woollen travelling-rug to cover his master's knees, while Kant seemed lost in deepest distraction, staring at me like a man who had seen a ghost. The fact that I had failed to understand yet again what, according to him, I ought to have understood seemed to have pitched him into a pit of depression.

'Something has frightened him, sir,' Johannes whispered.

'Let's take him home quickly, Johannes,' I said, as the valet prepared to leave the coach and take charge of the horse. 'I will walk back to Sturtenstra.s.se.'

I sat on the bench across from Professor Kant as the vehicle pulled away, uncertain whether to speak in an attempt to comfort him, or to remain silent. I might have been alone in the embalming room with the body of a dead Egyptian who was about to be mummified. His state was catatonic. He did not speak, or make a sound, as we drove the rest of the way to his house. Johannes jumped down at the gate, hitched the horse, and together we helped Kant to the ground, supporting him up the garden path as far as the front door.

'He has taken a fever,' Johannes whispered over his master's drooping head. Kant seemed to have lost the use of his legs, which trailed behind him, the toes of his boots dragging pigeon-toed on the paving-stones.

'Let's get him to bed,' I said.

Kant was ill. His face was pale, his breathing troubled; he seemed bereft of strength, his life force quite dissolved away.

We helped him across the hall, taking his arms on our shoulders, then we literally carried him up the stairs to his chamber. Johannes was a true tower of strength, somehow managing to do far more than I, and all the while carrying a lantern. In better circ.u.mstances, the fact that I was privileged to enter the sancta sanctorum of Professor Kant, by which I mean his private study and bedchamber, would have been a cause for elation. None of his friends or biographers had ever been allowed in there. Despite the fact that all my attention and concern were so concentrated on his well-being, I could not help but cast a quick glance around. The room was far smaller than I could have imagined. 'Monastic' was the word I would have chosen to describe it. A narrow cot stood hard up against one wall, a little chest of drawers by another, a tiny writing desk and a chair pressed close to the third wall. The fourth wall was taken up by a narrow slit of a window looking onto the rear garden of the house. Everything appeared to be sober, neat, functional, and I was moved by the thought that Immanuel Kant had written out sections of his monumental works at that very desk, including his latest, unseen treatise.

At the same time, my awe was stifled by the peculiar odour in that room. It simply could not be ignored. The narrow window I had noted to my left, looking onto the garden, had apparently never been opened. The air in the room was stale and mouldy, I would have said, as if the ceiling, floor and furniture were infected with woodworm, or dry rot. The atmosphere was impregnated with the smell of age and overused bedclothes which had never been adequately or frequently aired. I could not ignore the dry acridity of it. Without a doubt, Johannes took good care of his master, but I silently made a wish that he would attend more carefully to the laundry and house cleaning. What made it even more odd was the fact that all the other rooms in the house were immaculately clean and dusted. I jotted down a mental note to remind him of my critical observations before I left the house. But first, we had to get Kant into bed. As the light of the lantern fell on the pillowcase, a pale grey cloud seemed to shift and dissolve.

'What's that on the bed?' I whispered, breathing heavily after the effort of struggling up the narrow staircase with the inert body.

'Fleas, sir,' Johannes replied calmly.

My anger flared. 'The mattress needs disinfesting!'

'Oh, he won't have that, sir,' the servant responded blandly. 'Professor Kant has a method of his own to keep them off. It doesn't work, but he won't be moved.'

We had had similar problems at home two summers before. The fleas had invaded all the bedrooms and made our lives a misery until Lotte came up with a solution. She left a sheepskin out on the landing for two days and nights, then she rolled it up and burnt it out in the garden, far from the house. She and the children watched with glee as the poor fleas leapt up and down in the flames, crackling and popping, unable to escape their immolation.

'It's the only thing we've ever argued about,' Johannes continued. 'He says that lack of air and light will kill them off, and ordered me to stop up the window. Martin Lampe was a firm believer in the notion. That man's a constant presence here. Sometimes it seems as if he never left the house! Professor Kant has called me by his name on more occasions than I can count.'

Abruptly, he turned his attention to his master, preparing him for bed with a practised mixture of coaxing and firmness. 'Come, come, Herr Professor!' he called.

Sitting stiffly to attention on the edge of the bed while Johannes undressed him and put him into his nightgown, Professor Kant might have been a helpless infant waiting for his nurse to step up, turn the sheets, and hurry him to the Land of Nod. But unlike any child that I have ever known, he was struck dumb. He did not acknowledge my own presence by so much as a look. Johannes pulled back the covers and puffed up the pillows, ready to receive him.

Kant seemed lost in a deep trance as he settled back on the mattress and the eiderdown was pulled up to his chin. Though I felt better for seeing him safely to his own house, the fact that he was so completely pa.s.sive did not augur well. The troubled frown on the face of Johannes reflected my own concern.

'My work...It must be finished...'

The low murmur came from the bed. Johannes was standing over Kant, staring down at his master. 'Herr Professor?' he called, his voice too loud in the m.u.f.fled silence of the room.

'Professor Kant,' I urged, stepping up to the flea-ridden bed myself. 'Is all well with you, sir?'

Kant's left eye flashed open and he stared at me for a moment.

'A cold-blooded murderer,' he muttered. 'He bows to no one...'

He repeated the last two words over and over again.

'What is he saying, Herr Procurator?' Johannes whispered across the bed.

I shook my head, wanting silence, wanting Kant to stop this raving. My mind was in a whirl. Did he view my failure to catch the murderer as the defeat of Rationality and a.n.a.lytical Science? Had the killer overstepped some mark that only Kant could see? Could this threat to the world as he conceived it account for his altered state of mind?

Suddenly, Professor Kant let out a shrill whimper.

'Oh, Lord!' Johannes exclaimed. 'He needs help, sir. Call a doctor!'

'Who takes care of him?' I asked.

'He treats himself, as a rule. His knowledge of physic is beyond the skills of most of the physicians in Konigsberg...'

'In this state,' I insisted, 'he cannot help himself. He needs to be bled and poulticed. We need a professional.'

'There is a doctor living close by. He sometimes takes tea with my master. Perhaps he would be...' Johannes seemed to waver, as if crushed beneath the new responsibility that had been unexpectedly thrust upon him. 'But then again...'

A single glance at Professor Kant was enough to tell me that the time for hesitation was past. His eyes were closed, his face pale and expressionless, his respiration shallow and laboured.

'Where does this doctor live?' I asked.

'At the end of the street, sir. The first house on the left.'

I turned without another word and ran, the voice of Johannes following me down the stairs.

'But the man is Italian, sir, and he's very young!'

Five minutes later, short of breath, I reached the door of 'Dott. Danilo Gioacchini, Medico-Chirurgo', as the bra.s.s plaque described him. Beyond the door, I thought I heard the m.u.f.fled sound of crying, and almost feared to break in on some domestic crisis. The house was made of weathered clapperboard that had once been painted blue, but now was a sadly faded grey. Crushed in between more substantial brick buildings on either side, I wondered whether its air of genteel poverty mirrored the cramped situation of the people living there. Was that the cause of the tears? It could not be easy for an Italian to make his way in Konigsberg, despite the friendship of Immanuel Kant. Foreigners were held in low regard, Papists even more so, not only by the likes of Agneta Susterich and Johannes Odum, but by every devout Pietist.

But what else could I do? I raised the iron knocker which was shaped like a closed fist, and let it drop. A moment later, the door opened a crack to reveal the face of a pretty, dark-haired woman. Standing by her knee, holding tightly to the young woman's skirts, a little girl of two or three years of age stared solemnly up at me.

'I am looking for the doctor,' I said, choosing my words with care for fear of not being understood. If this was the doctor's wife, she had probably come with him from Italy. 'It concerns Professor Kant...'

The name of Kant brought a fleeting smile to the housewife's lips.

'Danilo!' she called, turning towards the interior of the house, opening the door wide for me, and waving me to enter.

A moment later, the doctor himself appeared in the hall. He was, indeed, young, thirty-five at the most, though his long blond hair was thinning. Tall, slim, stylishly dressed in a high-collared jacket of black velvet, he welcomed me with a warm smile and sparkling brown eyes. Cradled one in each arm, he held up two identical infants which might have been born within the week. Both babies were screaming with all the strength in their tiny lungs.

'Twins!' he said. From the sudden creasing of his brow I could not have guessed whether he was proud of the fact, or apologising for the disturbance.