He looked towards the bunk. The boy was voiding his bladder; but that act was simply a symptom of something else altogether. Beneath the blanket, Billy's body was moving in a dozen ways that his bonds should have prevented. It took Cleve a few moments to shake off lethargy, and seconds more to realize what was happening. Billy was changing.

Cleve tried to stand upright, but his lower limbs were dead from sitting so still for so long. He almost fell forward across the cell, and only prevented himself by throwing out an arm to grasp the chair. His eyes were glued to the gloom of the lower bunk. The movements were increasing in scale and complexity. The blanket was pitched off. Beneath it Billy's body was already beyond recognition; the same terrible procedure as he had seen before, but in reverse. Matter gathering in buzzing clouds about the body, and congealing into atrocious forms. Limbs and organs summoned from the ineffable, teeth shaping themselves like needles and plunging into place in a head grown large and swelling still. He begged for Billy to stop, but with every drawn breath there was less of humanity to appeal to. The strength the boy had lacked was granted to the beast; it had already broken almost all its constraints, and now, as Cleve watched, it struggled free of the last, and rolled off the bunk onto the floor of the cell.

Cleve backed off towards the door, his eyes scanning Billy's mutated form. He remembered his mother's horror at earwigs and saw something of that insect in this anatomy: the way it bent its shiny back upon itself, exposing the paddling intracies that lined its abdomen. Elsewhere, no analogy offered a hold on the sight. Its head was rife with tongues, that licked its eyes clean in place of lids, and ran back and forth across its teeth, wetting and re-wetting them constantly; from seeping holes along its flanks came a sewer stench. Yet even now there was a residue of something human trapped in this foulness, its rumour only serving to heighten the filth of the whole. Seeing its hooks and its spines Cleve remembered Lowell's rising scream; and felt his own throat pulse, ready to loose a sound its equal should the beast turn on him.

But Billy had other intentions. He moved - limbs in horrible array - to the window, and clambered up, pressing his head against the glass like a leech. The music he made was not like his previous song - but Cleve had no doubt it was the same summoning. He turned to the door, and began to beat upon it, hoping that Billy would be too distracted with his call to turn on him before assistance came.

'Quickly! For Christ's sake! Quickly!' He yelled as loudly exhaustion would allow, and glanced over his shoulder once to see if Billy was coming for him. He was not; he was still clamped to the window, though his call had all but faltered. Its purpose was achieved. Darkness was tyrant in the cell.

Panicking, Cleve turned back to the door and renewed his tattoo. There was somebody running along the landing now; he could hear shouts and imprecations from other cells. 'Jesus Christ, help me!' he shouted. He could feel a chill at his back. He didn't need to turn to know what was happening behind him. The shadow growing, the wall dissolving so that the city and its occupant could come through. Tait was here. He could feel the man's presence, vast and dark. Tait the child-killer, Tait the shadow-thing, Tait the transformer. Cleve beat on the door 'til his hands bled. The feet seemed a continent away. Were they coming? Were they coming?

The chill behind him became a blast. He saw his shadow thrown up on to the door by flickering blue light; smelt sand and blood.

And then, the voice. Not the boy, but that of his grandfather, of Edgar St Clair Tait. This was the man who had pronounced himself the Devil's excrement, and hearing that abhorrent voice Cleve believed both in Hell and its master, believed himself already in the bowels of Satan, a witness to its wonders.

'You are too inquisitive.' Edgar said, 'It's time you went to bed.'

Cleve didn't want to turn. The last thought in his head was that he should turn and look at the speaker. But he was no longer subject to his own will; Tait had fingers in his head and was dabbling there. He turned, and looked.

The hanged man was in the cell. He was not that beast Cleve had half-seen, that face of pulp and eggs. He was here in the flesh; dressed for another age, and not without charm. His face was well-made; his brow wide, his eyes unflinching. He still wore his wedding-ring on the hand that stroked Billy's bowed head like that of a pet dog.

Time to die, Mr Smith,' he said.

On the landing outside, Cleve heard Devlin shouting. He had no breath left to answer with. But he heard keys in the lock or was that some illusion his mind had made to placate his panic?

The tiny cell was full of wind. It threw over the chair and table, and lifted the sheets into the air like childhood ghosts. And now it took Tait, and the boy with him; sucked them back into the receding perspectives of the city.

'Come on now - ' Tait demanded, his face corrupting, 'we need you, body and soul. Come with us, Mr Smith. We won't be denied.'

'No!' Cleve yelled back at his tormentor. The suction was plucking at his fingers, at his eye-balls. 'I won't -'

Behind him, the door was rattling.

'I won't, you hear!'

Suddenly, the door was thrust open, and threw him forward into the vortex of fog and dust that was sucking Tait and his grandchild away. He almost went with them, but that a hand grabbed at his shirt, and dragged him back from the brink, even as consciousness gave itself up.

Somewhere, far away, Devlin began to laugh like a hyena. He's lost his mind, Cleve decided; and the image his darkening thoughts evoked was one of the contents of Devlin's brain escaping, through his mouth as a flock of flying dogs.

He awoke in dreams; and in the city. Woke remembering his last conscious moments: Devlin's hysteria, the hand arresting his fall as the two figures were sucked away in front of him. He had followed them, it seemed, unable to prevent his comatose mind from retreading the familiar route to the murderers' metropolis. But Tait had not won yet. He was still only dreaming his presence here. His corporeal self was still in Pentonville; his dislocation from it informed his every step.

He listened to the wind. It was eloquent as ever: the voices coming and going with each gritty gust, but never, even when the wind died to a whisper, disappearing entirely. As he listened, he heard a shout. In this mute city the sound was a shock; it startled rats from their nests and birds up from some secluded plaza.

Curious, he pursued the sound, whose echoes were almost traced on the air. As he hurried down the empty streets he heard further raised voices, and now men and women were appearing at the doors and windows of their cells. So many faces, and nothing in common between one and the next to confirm the hopes of a physiognomist. Murder had as many faces as it had occurrences. The only common quality was one of wretchedness, of minds despairing after an age at the site of their crime. He glanced at them as he went, sufficiently distracted by their looks not to notice where the shout was leading him until he found himself once more in the ghetto to which he had been led by the child.

Now he rounded a corner and at the end of the cul-de-sac he'd seen from his previous visit here (the wall, the window, the bloody chamber beyond) he saw Billy, writhing in the sand at Tait's feet. The boy was half himself and half that beast he had become in front of Cleve's eyes. The better part was convulsing in its attempt to climb free of the other, but without success. In one moment the boy's body would surface, white and frail, only to be subsumed the next into the flux of transformation. Was that an arm forming, and being snatched away again before it could gain fingers?; was that a face pressed from the house of tongues that was the beast's head? The sight defied analysis. As soon as Cleve fixed upon some recognizable feature it was drowned again.