Arthur took a deep breath, and for a moment marvelled at just how deeply he could breathe now, his asthma gone with his old human self, all earthly frailties being left behind in his transition to a new, immortal form. Then he took the mirror that was the Fifth Key out of his pocket and held it up in front of his face. An intense light shone around it in a fierce corona, but Arthur looked directly at the mirror without difficulty, seeing only the reflection of his own changing face, his more regular nose, his whiter teeth, and his silkier hair.

Leaf shielded her eyes with her arm, and even the sleepwalkers turned their heads away and screwed their eyes shut tighter as they kept shuffling forward.

I really hope this works, thought Arthur. It has to work. Only I wish I could have checked with Dr Scamandros, because I don’t really know what . . .

Arthur grimaced, banished his fearful inner voice, and focussed on what he wanted the Fifth Key to do. Because it seemed easier and somehow made it sound more like it would happen, he spoke aloud to the Key.

‘Fifth Key of the Architect! I, Arthur Penhaligon, Rightful Heir of the Architect, um . . . I desire you to shield this city inside a bubble that keeps it separate from Earth, a bubble that will protect the city and keep everyone in it safe from all harm, and . . . well . . . that’s it . . . thanks.’

The mirror flashed and this time Arthur did have to blink. When he opened his eyes, he felt momentarily unsteady on his feet and had to raise his arms like a tightrope-walker to regain his balance. In that instant, he saw that everyone else had stopped moving. Leaf and the line of sleepers were still, as if they had been snap-frozen. Many of the sleepers had one foot slightly off the ground, a position that no one could possibly keep up in normal circumstances.

It was also newly quiet. Arthur couldn’t hear the helicopters or gunfire or any other noise. It was like being in a waxwork museum after closing time, surrounded by posed statues.

Arthur slipped the mirror into his pocket and ran his fingers through his hair – which had grown considerably longer than he cared for, though it somehow stayed out of his face.

‘Leaf?’ he said tentatively, walking over to tap his friend lightly on the shoulder. ‘Leaf? Are you okay?’

Leaf didn’t move. Arthur looked at her face. Her eyes were open but her pupils didn’t move when he waved his finger back and forth. He couldn’t even tell if she was breathing.

Arthur felt a sudden panic rise in him.

I’ve killed them, he thought. I was trying to save them, but I killed them . . .

He touched Leaf on the shoulder again, and though a faint nimbus of red light sprang up around his fingers, she still didn’t move or react in any way.

Arthur stepped back and looked around. There was a faint red glow around each of the sleepers too, and when he walked over and touched them, this light also grew momentarily brighter. Arthur didn’t know what the glow meant, but he found it slightly comforting, as it suggested some sorcerous effect was active and he hadn’t just killed everyone.

But I don’t even know if I have protected us from the nukes, Arthur thought. What time is it?

He turned and ran down the hall, through the next two wards, and out into the lobby. From there it took him a minute to find the office and a clock. It had stopped at exactly 11:57, the second hand quivering on the twelve. The clock also had a faint red sheen, and there were ghostly scarlet shadows behind the second and hour hands.

Arthur ran outside. The front doors slammed shut behind him with a sound all too like the trump of doom. He slid to a halt just before he fell down the wheelchair ramp, because everywhere he looked was tinted red. It was like looking at the world through red sunglasses on an overcast day, because the night sky had been replaced by a solid red that was buzzing and shifting and hard to look at, like a traffic light viewed far too close.

‘I guess I’ve done something,’ Arthur said to himself. ‘I just don’t know exactly what . . .’

He walked a little farther, out into the car park. Something caught his eye, up in the sky, a small silhouette. He peered at it for a few seconds before he worked out that it was a helicopter gunship. But it wasn’t moving. It was like a model stuck on a piece of wire in a diorama, just hanging there in the red-washed sky.

Stuck in a moment of time.

That’s why everyone is frozen in place, Arthur thought. I’ve stopped time . . . that’s how the Key is keeping everyone in the city safe . . .

If time was only frozen or slowed inside a bubble around the city, it could start again, or be started again by some other power. Which meant that the nuclear strike on East Area Hospital would still happen. He hadn’t saved the city from the attack. He’d just postponed it . . .

‘If it isn’t one thing, it’s another,’ whispered Arthur. He looked along the empty street, all strange and red-hued, and wondered if he should run over to his home and see if his family was all right. Maybe he could carry them down into the cellar . . . but if he did that, he might be wasting time better spent learning how to protect everyone else. He couldn’t carry everyone in danger to safety.

He’d gained a breathing space for the city, and he could extend it by going back to the House. If he left now, he should be able to return to almost exactly the same time, even if he spent days or even weeks in the House.

Should is not the same as definitely, thought Arthur grimly. I wish I understood the time relativities better. I wish I knew more about how to use the Keys. I wish I’d never, ever got involved in all –

Arthur stopped himself.

‘If I wasn’t involved, I’d be dead,’ he said aloud. ‘I just have to get on with it.’

Getting on with it, Arthur thought, included facing up to things. He held his hand up close to his face and looked at the crocodile ring. Even in the weird red light, he could see it clearly. The diamond eyes of the crocodile looked baleful, as dark as dried black blood rather than their usual pink. The ten marked sections of its body, each inscribed with a Roman numeral, recorded the degree of sorcerous contamination in his blood and bone. If more than six sections had turned from silver to gold, Arthur would be permanently tainted with sorcery and irretrievably destined to become a Denizen.

Arthur slowly turned the ring around, to see how far the gold transformation had progressed, counting in his head. One, two, three, four, five . . . he knew it had gone that far already. He turned the ring again, and saw the gold had completely filled the fifth segment, and had flooded over, almost completely across the sixth segment.

I am . . . I am going to be a Denizen.

Arthur took a deep, shuddering breath and looked again, but there was no change in the ring. It was six parts gold. He was sixty per cent immortal.

‘No turning back now,’ said Arthur to the red world around him. ‘Time to get back to work.’

He looked away from the ring and lowered his hand. Bending his head for a moment, he drew out the Fifth Key from his pocket and raised it high. According to Dame Primus, the mirror of Lady Friday could take him to anywhere he had previously seen within the House, if there was a reflective surface there.

Arthur pictured the throne room in the Lower House, the big audience chamber where he had met with Dame Primus and everyone before he was drafted into the Army of the Architect. It was the place he could most easily visualise in Monday’s Dayroom, because it didn’t have much detail and was so over the top in decoration – including floors of reflective marble.

‘Fifth Key, take me to the throne room in Monday’s Dayroom.’

The Fifth Key shivered in Arthur’s hand and a beam of white light sprang from it, banishing the red. The light formed a perfect, upright rectangle, exactly like a door.

Arthur walked into the rectangle of light and disappeared from his own city, from his Earth, perhaps never to return.

THREE

THE THRONE ROOM was empty. Otherwise it looked the same as it had when Arthur had last been there: like one enormous, ritzy, poorly conceived hotel bathroom. It was about as large as a big city theatre, and the walls, floor and ceiling were all lined with gold-veined white marble that was polished to a highly reflective sheen.

The vast, red-iron round table was still in the middle of the chamber, with the hundred tall-backed white chairs around it. On the other side, Arthur’s own high throne of gilded iron sat next to the rainbow chair of Dame Primus.

‘Hello!’ Arthur called out. ‘Anyone here?’

His voice filled the empty space, and the echoes were the only answer. Arthur sighed and strode over to the door, his footsteps setting up another echo behind him, so it sounded like he was being followed by many small, close companions.

The corridor outside was still crowded with thousands of bundles of paper, each tied with a red ribbon and stacked like bricks. Unlike last time, there were no Commissionaire Sergeants standing at attention in the gaps between the piles of paperwork.

‘Hello!’ Arthur shouted again. He ran down the corridor, pausing several times to see if there were doors leading out. Eventually he came to the end of the corridor, where he found a door propped half open and partially covered in bundles of paper. He could only see it because one of the piles had collapsed.

There were still no Denizens. Arthur rushed through the half-open door and along another empty corridor, pushing doors open as he passed them without encountering anyone else.

‘Hello! Anyone here?’ he shouted every few yards, but no answer came.

Finally he came to a pair of tall, arched doors of dark oak. They were barred, but he easily lifted the bar – not even pausing to marvel that he had grown so strong that he could move a piece of timber that must weigh several hundred pounds. Once the bar was up, the door was easily pushed open.

This particular door led outside. Arthur had expected to see the lake and the rim of the crater that surrounded the Dayroom, and the ceiling of the Lower House above. Instead he saw a vast, arching wave of Nothing that rose way above him, a wave that had already eaten up everything but the small villa behind him. He felt like he was on a small hilltop, the last piece of dry land ahead of a tsunami – but the wave was coming, climbing high, and it would soon crash down to destroy even this last refuge.

Arthur turned to run, his heart suddenly hammering in fear, his mouth dry as dust. But after that first panicked step, he stopped and turned back. The wave of Nothing was coming down, and he didn’t have time to run. He doubted the Fifth Key could protect him from such a vast influx of Nothing. At least not unless he actively directed its power.

I have to do something, thought Arthur, and he acted with the speed of that thought.

Even as the wave of Nothing crashed down upon him, he raised the mirror and held it high, pushing it toward the dark, falling sky.

‘Stop!’ he shouted, his voice raw with power, every part of his mind focussed on stopping the tsunami of Nothing. ‘Stop! By the Keys I hold, I order the Nothing to stop! House, you must hold against the Void!’

Blinding light shone from the mirror, hot white beams that set the air on fire as they shot out and up, striking the onrush of Nothing, splashing across the face of the darkness, small marks of brilliance upon the void.

Arthur felt a terrible pain blossom in his heart. The pain spread, racing down his arms and legs. Awful cracking sounds came from his joints, and he had to screw his eyes shut and scream as his teeth rearranged themselves into a more perfect order in his jaw. Then his jaw itself moved and he felt the plates of bone in his skull shift and change.

But still he kept holding the mirror up above his head, even as he fell to his knees. He used the pain, channelling it to fuel his concentration, directing his will against the rush of Nothing.

Finally, it was too much. Arthur could neither bear the pain nor continue the effort. He fell forward on his face, his screams becoming dull sobs. His strength used up, he dropped the Fifth Key on the narrow band of grass that was all that remained of the lawns that had once surrounded the Dayroom villa.

He lay there, partially stunned, awaiting annihilation, knowing that he had failed and that when he died, the rest of the Universe would follow. All he loved would be destroyed, back on Earth, in the House, and in the worlds beyond.

A minute passed, and then another, and the annihilation didn’t happen. As the pain in his bones ebbed, Arthur groaned and rolled over. He would face the Nothing, rather than be snuffed out by it while he lay defeated upon the grass.

The first thing he saw was not incipient destruction but a delicate tracery of glowing golden lines, like a web or a mesh net of light thrown against the sky. It was holding back the great mass of threatening darkness, but Arthur could feel the pressure of the Nothing, could feel the infinite Void pushing against his restraints. He knew that it would soon overcome his net of light and once again advance.

Arthur picked up the mirror and staggered to his feet. The ground felt further away than normal, and he lost his balance for a moment, swaying on the spot. The sensation passed as he shook his head, and he ran back to the open doors. There was a telephone in the library, he knew, and he needed to call and find out where in the House was safe, instead of going somewhere that might have already succumbed to Nothing. He didn’t want to think about what would happen if he used the Fifth Key to take him straight into the Void, though it probably would have the advantage of being quick . . .

Or maybe the Key would protect me for a little while, Arthur thought with sudden nausea. Long enough to feel the Nothing dissolve my flesh . . .

He hurried along the main corridor until he saw a door he recognised. Darting through it, he leapt up the steps four at a time, bouncing off the walls as he tried to take the turns in the staircase too fast.

At the top, he sprinted down another long corridor, this one also narrowed by piles of records, many of them written on papyrus or cured hides instead of paper. Pausing to shift a six-foot-high stone tablet that had fallen and blocked the way, Arthur didn’t bother with the handle of the door at the end but kicked it open and stumbled into the library beyond.