And then, as he watched the dunes and the sky, mesmerized by their blankness, he heard a sound and glanced over his shoulder to see a smiling man, dressed in what was surely his Sunday finery, walking out of the city towards him. He was carrying a knife; the blood on it, and on his hand and shirt-front, was wet. Even in his dream-state, and immune, Cleve was intimidated by the sight and stepped back - a word of self-defence on his lips. The smiling man seemed not to see him however, but advanced past Cleve and out into the desert, dropping the blade as he crossed some invisible boundary. Only now did Cleve see that others had done the same, and that the ground at the city limit was littered with lethal keepsakes - knives, ropes (even a human hand, lopped off at the wrist) - most of which were all but buried.

The wind was bringing the voices again: tatters of senseless songs and half-finished laughter. He looked up from the sand. The exiled man had gone out a hundred yards from the city and was now standing on the top of one of the dunes, apparently waiting. The voices were becoming louder all the time. Cleve was suddenly nervous. Whenever he had been here in the city, and heard this cacophony, the picture he had conjured of its originators had made his blood run cold. Could he now stand and wait for the banshees to appear? Curiosity was discretion's better. He glued his eyes to the ridge over which they would come, his heart thumping, unable to look away. The man in the Sunday suit had begun to take his jacket off. He discarded it, and began to loosen his tie.

And now Cleve thought he saw something in the dunes, and the noise rose to an ecstatic howl of welcome. He stared, defying his nerves to betray him, determined to look this horror in its many faces -

Suddenly, above the din of their music, somebody was screaming; a man's voice, but high-pitched, gelded with terror. It did not come from here in the dream-city, but from that other fiction he occupied, the name of which he couldn't quite remember. He pressed his attention back to the dunes, determined not to be denied the sight of the reunion about to take place in front of him. The scream in that nameless elsewhere mounted to a throat-breaking height, and stopped. But now an alarm bell was ringing in its place, more insistent than ever. Cleve could feel his dream slipping.

'No ...' he murmured,'... let me see ...'

The dunes were moving. But so was his consciousness - out of the city and back towards his cell. His protests brought him no concession. The desert faded, the city too. He opened his eyes. The lights in the cell were still off: the alarm bell was ringing. There were shouts in cells on the landings above and below, and the sound of officers' voices, raised in a confusion of enquiries and demands.

He lay on his bunk a moment, hoping, even now, to be returned into the enclave of his dream. But no; the alarm was too shrill, the mounting hysteria in the cells around too compelling. He conceded defeat and sat up, wide awake.

'What's going on?' he said to Billy.

The boy was not standing in his place by the wall. Asleep, for once, despite the din.

'Billy?

Cleve leaned over the edge of his bunk, and peered into the space below. It was empty. The sheets and blankets had been thrown back.

Cleve jumped down from his bunk. The entire contents of the cell could be taken at two glances, there was nowhere to hide. The boy was not to be seen. Had he been spirited away while Cleve slept? It was not unheard of; this was the ghost train of which Devlin had warned: the unexplained removal of difficult prisoners to other establishments. Cleve had never heard of this happening at night, but there was a first time for everything.

He crossed to the door to see if he could make some sense of the shouting outside, but it defied interpretation. The likeliest explanation was a fight, he suspected: two cons who could no longer bear the idea of another hour in the same space. He tried to work out where the initial scream had come from, to his right or left, above or below; but the dream had confounded all direction.

As he stood at the door, hoping an officer might pass by, he felt a change in the air. It was so subtle he scarcely registered it at first. Only when he raised his hand to wipe sleep from his eyes did he realize that his arms were solid gooseflesh.

From behind him he now heard the sound of breathing, or a ragged parody of same.

He mouthed the word 'Billy' but didn't speak it. The gooseflesh had found his spine; now he began to shake. The cell wasn't empty after all; there was somebody in the tiny space with him.

He screwed his courage tight, and forced himself to turn around. The cell was darker than it had been when he woke; the air was a teasing veil. But Billy was not in the cell; nobody was.

And then the noise came again, and drew Cleve's attention to the bottom bunk. The space was pitch-black, a shadow - like that on the wall - too profound and too volatile to have natural origins. Out of it, a croaking attempt at breath that might have been the last moments of an asthmatic. He realized that the murk in the cell had its source there - in the narrow space of Billy's bed; the shadow bled onto the floor and curled up like fog on to the top of the bunk.

Cleve's supply of fear was not inexhaustible. In the past several days he had used it up in dreams and waking dreams; he'd sweated, he'd frozen, he'd lived on the edge of sane experience and survived. Now, though his body still insisted on gooseflesh, his mind was not moved to panic. He felt cooler than he ever had; whipped by recent events into a new impartiality. He would not cower. He would not cover his eyes and pray for morning, because if he did one day he would wake to find himself dead and he'd never know the nature of this mystery.

He took a deep breath, and approached the bunk. It had begun to shake. The shrouded occupant in the lower tier was moving about violently.

'Billy,' Cleve said.

The shadow moved. It pooled around his feet; it rolled up into his face, smelling of rain on stone, cold and comfortless.

He was standing no more than a yard from the bunk, and still he could make nothing out; the shadow defied him. Not to be denied sight, he reached towards the bed. At his solicitation the veil divided like smoke, and the shape that thrashed on the mattress made itself apparent.

It was Billy, of course; and yet not. A lost Billy, perhaps, or one to come. If so, Cleve wanted no part of a future that could breed such trauma. There, on the lower bunk, lay a dark, wretched shape, still solidifying as Cleve watched, knitting itself together from the shadows. There was something of a rabid fox in its incandescent eyes, in its arsenal of needle-teeth; something of an upturned insect in the way it was half curled upon itself, its back more shell than flesh and more nightmare than either. No part of it was fixed. Whatever figuration it had (perhaps it had many) Cleve was watching that status dissolve. The teeth were growing yet longer, and in so doing more insubstantial, their matter extruded to the point of frailty, then dispersed like mist; its hooked limbs, pedalling the air, were also growing paltry. Beneath the chaos he saw the ghost of Billy Tait, mouth open and babbling agonies, striving to make itself known. He wanted to reach into the maelstrom and snatch the boy out, but he sensed that the process he was watching had its own momentum and it might be fatal to intervene. All he could do was stand and watch as Billy's thin white limbs and heaving abdomen writhed to slough off this dire anatomy. The luminous eyes were almost the last to go, spilling out from their sockets on myriad threads and flying off into black vapour.

At last, he saw Billy's face, truant clues to its former condition still flickering across it. And then, even these were dispersed, the shadows gone, and only Billy was lying on the bunk, naked and heaving with the exertion of his anguish. He looked at Cleve, his face innocent of expression. Cleve remembered how the boy had complained to the creature from the city.'... it hurts ...' he'd said, hadn't he?,'... you didn't tell me how much it hurts...'. It was the observable truth. The boy's body was a wasteland of sweat and bone; a more unappetising sight was scarcely imaginable. But human; at least that.