'I see.' And Hawksmoor watched Walter suddenly leave the room.

'I will have to do more tests, superintendent, but I'm almost sure that there are no prints.'

'Could the murderer have chilled his hands?'

That's possible, certainly. Or they might just have been very cold.'

'And if there was a struggle, I suppose the boy might have clutched the fingers to loosen them and then disturbed the prints?' Although this sounded like a question the pathologist did not answer it, and for the first time Hawksmoor stared down at the opened corpse. He knew it was not yet completely cold, and in that moment he felt its heat blasting his face, and as the air crumpled like silk around him it was his own body upon the table.

Walter was sitting with his head bowed forward over his knees when Hawksmoor eventually joined him in the corridor. He put his hand on the young man's shoulder: 'Well, Walter, what do you make of that timing?'

Walter looked up at him in alarm, and Hawksmoor averted his eyes for a moment. 'It's impossible, sir.'

'Nothing is impossible. The impossible does not exist. All we need is a new death, and then we can proceed from the beginning until we reach our end.'

'And what end is that, sir?'

'If I knew the end, I could begin, couldn't I? I can't have one without the other.' And he smiled at Walter's evident perplexity. 'Don't worry, I know what I'm doing. Just give me time. AH I need is time.'

'I'm not worried, sir.'

'Good. And since you're so happy you can go and see the father.

Tell him what we've found out. But don't tell him too much.'

And Walter sighed: Thank you very much. I appreciate the gesture, sir.'

Hawksmoor remembered another phrase which his colleagues used: 'Life is full of grief, Walter, life is full of grief.'

He walked back to St George's-in-the-East, which in his mind he had now reduced to a number of surfaces against which the murderer might have leaned in sorrow, desperation or even, perhaps, joy. For this reason it was worth examining the blackened stones in detail, although he realised that the marks upon them had been deposited by many generations of men and women. It was now a matter of received knowledge in the police force that no human being could rest or move in any area without leaving some trace of his or her identity; but if the walls of the Wapping church were to be analysed by emission spec troscopy, how many partial or residual spectra might be detected?

And he had an image of a mob screaming to be set free as he guided his steps towards the tower which rose above the houses cluttered around Red Maiden Lane, Crab Court and Rope Walk. To the right of it he heard a confused murmur of voices, and to the left of it he heard the sounds from the river, until at last in tront of him he could see, even in the light of the early afternoon, the diffused whiteness of the arc-lights which had been erected around the scene of the small boy's murder. Only two detective constables remained on the site, and their task was to guard it from the sightseers who had come to gaze upon this place and who would otherwise have collected pieces of stone or wood as souvenirs of this death. Hawksmoor stood watching the scene for a few minutes until he was roused by the bell striking the hour: he glanced up at the church (which by some trick of perspective seemed about to fall on him), and then he wandered away from its grounds and walked towards the Thames.

The gloom of the secluded wharves and muddy banks had always attracted him and, when he came to Wapping Reach, he stared down at the shadows of the clouds moving quickly over the surface of the water. But when he removed his glasses and again looked down, it seemed to him that the river itself was perpetually turning and spinning: it was going in no certain direction, and Hawksmoor felt for a moment that he might fall into its darkness. Two men passed on a small boat -one of them was laughing or grimacing, and seemed to be pointing at Hawksmoor, but his voice did not carry over the water; Hawksmoor watched this dumb-show pass until it turned the bend towards Tower Bridge and vanished as suddenly as it had arrived.

It had started to rain and he began walking along the riverbank away from Wapping and towards Limehouse. He turned left down Butcher Row, for he could see now the tower of St Anne's Limehouse ahead of him, and he entered that area of abandoned houses and derelict land which still divides the city from the river. Then he stopped suddenly in confusion: the dampness had released a close, rank smell from the lush vegetation which spread over the stones and sprang up between wires, and he could see a vagrant squatting on the ground with his face turned up to catch the rain. So he turned away from this waste-land and crossed into Shoulder-of-Mutton Alley, and there was silence by the time he came to the front of St Anne's.

Hawksmoor could have produced a survey of the area between the two churches of Wapping and Limehouse, and given at the same time a precise account of the crimes which each quarter harboured. This had been the district of the CID to which he had been attached for some years, before he was assigned to the Murder Squad, and he had come to know it well: he knew where the thieves lived, where the prostitutes gathered, and where the vagrants came. He grew to understand that most criminals tend to remain in the same districts, continuing with their activities until they were arrested, and he sometimes speculated that these same areas had been used with similar intent for centuries past: even murderers, who rapidly became Hawksmoor's speciality, rarely moved from the same spot but killed again and again until they were discovered. And sometimes he speculated, also, that they were drawn to those places where murders had occurred before. In his own time in this district, there had been a house in Red Maiden Lane in which three separate murders had been perpetrated over a period of eight years, and the building itself gave such an impression to those who entered it that it had stayed unoccupied since the last killing. In Swedenborg Gardens Robert Haynes had murdered his wife and child, and it was Hawksmoor who was called when the remains were found beneath the floorboards; in Commercial Road there had been the ritual slaying of one Catherine Hayes, and then only last year a certain Thomas Berry had been stabbed and then mutilated in the alley beside St George's-in-the-East. It had been in this district, as Hawksmoor knew, that the Marr murders of 1812 had occurred -the perpetrator being a certain John Williams, who, according to De Quincey whose account Hawksmoor avidly read, 'asserted his own supremacy above all the children of Cain'. He killed four in a house by Ratcliffe Highway -a man, wife, servant and child -by shattering their skulls with a mallet and then gratuitously cutting their throats as they lay dying. Then, twelve days later and in the same quarter, he repeated his acts upon another family. He was transformed, again according to De Quincey, into a 'mighty murderer' and until his execution he remained an object of awe and mystery to those who lived in the shadow of the Wapping church. The mob tried to dismember his body when eventually it was brought in a cart to the place of burial -at the conflux of four roads in front of the church, where he was interred and a stake driven through his heart. And, as far as Hawksmoor knew, he lay there still: it was the spot where he had this morning seen the crowd pressing against the cordon set up by the police. And it did not take any knowledge of the even more celebrated Whitechapel murders, all of them conducted in the streets and alleys around Christ Church, Spitalfields, to understand, as Hawksmoor did, that certain streets or patches of ground provoked a malevolence which generally seemed to be quite without motive. And he knew, also, how many murders go undetected and how many murderers remain unknown.