'What, you mean the fabric of time and space being put through the wringer?' said IIa.

The architect gave his brother a look of faint admiration. It was an unusual remark for an accountant. Then his face returned to its previous look of faint terror.

'No, not that,' he said.

'Well, the sound of the very air itself being subjected to horrible tortures?'

'Not that, either,' said IIb, vaguely annoyed. 'I mean the creaking noise.'

Three more pyramids struck their discharges, which fizzled through the roiling clouds overhead and poured into the black marble above them.

'Can't hear anything like that,' said IIa.

'I think it's coming from the pyramid.'

'Well, you can put your ear against it if you like, but I'm not going to.'

The scaffolding swayed in the storm as they eased their way up another ladder, the heavy capstone rocking between them.

'I said we shouldn't do it,' muttered the accountant, as the stone slid gently on to his toes. 'We shouldn't have built this.'

'Just shut up and lift your end, will you?'

And so, one rocking ladder after another, the brothers Ptaclusp eased their bickering way up the flanks of the Great Pyramid, while the lesser tombs along the Djel fired one after another, and the sky streamed with lines of sizzling time.

It was around about this point that the greatest mathematician in the world, lying in cosy flatulence in his stall below the palace, stopped chewing the cud and realised that something very wrong was happening to numbers. All the numbers.

The camel looked along its nose at Teppic. Its expression made it clear that of all the riders in all the world it would least like to ride it, he was right at the top of the list. However, camels look like that at everyone. Camels have a very democratic approach to the human race. They hate every member of it, without making any distinctions for rank or creed.

This one appeared to be chewing soap.

Teppic looked distractedly down the shadowy length of the royal stables, which had once contained a hundred camels. He'd have given the world for a horse, and a moderately-sized continent for a pony. But the stables now held only a handful of rotting war chariots, relics of past glories, an elderly elephant whose presence was a bit of a mystery, and this camel. It looked an extremely inefficient animal. It was going threadbare at the knees.

'Well, this is it,' he said to Ptraci. 'I don't dare try the river during the night. I could try and get you over the border.'

'Is that saddle on right?' said Ptraci. 'It looks awfully funny.'

'It's on an awfully odd creature,' said Teppic. 'How do we climb on to it?'

'I've seen the camel drivers at work,' she replied. 'I think they just hit them very hard with a big stick.'

The camel knelt down and gave her a smug look.

Teppic shrugged, pulled open the doors to the outside world, and stared into the faces of five guards.

He backed away. They advanced. Three of them were holding the heavy Djel bows, which could propel an arrow through a door or turn a charging hippo into three tons of mobile kebab. The guards had never had to fire them at a fellow human, but looked as though they were prepared to entertain the idea.

The guard captain tapped one of the men on the shoulder, and said, 'Go and inform the high priest.'

He glared at Teppic.

'Throw down all your weapons,' he said.

'What, all of them?'

'Yes. All of them.'

'It might take some time,' said Teppic cautiously.

'And keep your hands where I can see them,' the captain added.

'We could be up against a real impasse here,' Teppic ventured. He looked from one guard to another. He knew a variety of methods of unarmed combat, but they all rather relied on the opponent not being about to fire an arrow straight through you as soon as you moved. But he could probably dive sideways, and once he had the cover of the camel stalls he could bide his time

And that would leave Ptraci exposed. Besides, he could hardly go around fighting his own guards. That wasn't acceptable behaviour, even for a king.

There was a movement behind the guards and Dios drifted into view, as silent and inevitable as an eclipse of the moon. He was holding a lighted torch, which reflected wild highlights on his bald head.

'Ah,' he said. 'The miscreants are captured. Well done.' He nodded to the captain. 'Throw them to the crocodiles.'

'Dios?' said Teppic, as two of the guards lowered their bows and bore down on him.

'Did you speak?'

'You know who I am, man. Don't be silly.'

The high priest raised the torch.

'You have the advantage of me, boy,' he said. 'Metaphorically speaking.'

'This is not funny,' said Teppic. 'I order you to tell them who I am.'

'As you wish. This assassin,' said Dios, and the voice had the cut and sear of a thermic lance, 'has killed the king.'

'I am the king, damn it,' said Teppic. 'How could I kill myself?'

'We are not stupid,' said Dios. 'These men know the king does not skulk the palace at night, or consort with condemned criminals. All that remains for us to find out is how you disposed of the body.'

His eyes fixed on Teppic's face, and Teppic realised that the high priest was, indeed, truly mad. It was the rare kind of madness caused by being yourself for so long that habits of sanity have etched themselves into the brain. I wonder how old he really is? he thought.

'These assassins are cunning creatures,' said Dios. 'Have a care of him.'

There was a crash beside the priest. Ptraci had tried to throw a camel prod, and missed.

When everyone looked back Teppic had vanished. The guards beside him were busy collapsing slowly to the floor, groaning.

Dios smiled.

'Take the woman,' he snapped, and the captain darted forward and grabbed Ptraci, who hadn't made any attempt to run away. Dios bent down and picked up the prod.

'There are more guards outside,' he said. 'I'm sure you will realise that. It will be in your interests to step forward.'

'Why?' said Teppic, from the shadows. He fumbled in his boot for his blowpipe.

'You will then be thrown to the sacred crocodiles, by order of the king,' said Dios.

'Something to look forward to, eh?' said Teppic, feverishly screwing bits together.

'It would certainly be preferable to many alternatives,' said Dios.

In the darkness Teppic ran his fingers over the little coded knobs on the darts. Most of the really spectacular poisons would have evaporated or dissolved into harmlessness by now, but there were a number of lesser potions designed to give their clients nothing more than a good night's sleep. An assassin might have to work his way to an inhume past a number of alert bodyguards. It was considered impolite to inhume them as well.

'You could let us go,' said Teppic. 'I suspect that's what you want, isn't it? For me to go away and never come back? That suits me fine.'

Dios hesitated.

'You're supposed to say “And let the girl go”,' he said.

'Oh, yes. And that, too,' said Teppic.

'No. I would be failing in my duty to the king,' said Dios.

'For goodness sake, Dios, you know I am the king!'

'No. I have a very clear picture of the king. You are not the king,' said the priest.

Teppic peered over the edge of the camel stall. The camel peered over his shoulder.

And then the world went mad.

All right, madder.

All the pyramids were blazing now, filling the sky with their sooty light as the brothers Ptaclusp struggled to the main working platform.

IIa collapsed on the planking, wheezing like an elderly bellows. A few feet away the sloping side was hot to the touch, and there was no doubt in his mind now that the pyramid was creaking, like a sailing ship in a gale. He had never paid much attention to the actual mechanics as opposed to the cost of pyramid construction, but he was pretty certain that the noise was as wrong as II and II making V.

His brother reached out to touch the stone, but drew his hand back as small sparks flashed around his fingers.

'You can feel the warmth,' he said. 'It's astonishing!'

'Why?'

'Heating up a mass like this. I mean, the sheer tonnage...'

'I don't like it, Two-bee,' IIa quavered. 'Let's just leave the stone here, shall we? I'm sure it'll be all right, and in the morning we can send a gang up here, they'll know exactly what-'

His words were drowned out as another flare crackled across the sky and hit the column of dancing air fifty feet above them. He grabbed part of the scaffolding.

'Sod take this,' he said. 'I'm off.'

'Hang on a minute,' said IIb. 'I mean, what is creaking? Stone can't creak.'

'The whole bloody scaffolding is moving, don't be daft!' He stared goggle-eyed at his brother. 'Tell me it's the scaffolding,' he pleaded.

'No, I'm certain this time. It's coming from inside.' They stared at one another, and then at the rickety ladder leading up to the tip, or to where the tip should be.

'Come on!' said IIb. 'It can't flare off, it's trying to find ways of discharging-'

There was a sound as loud as the groaning of continents.

Teppic felt it. He felt that his skin was several sizes too small. He felt that someone was holding his ears and trying to twist his head off.

He saw the guard captain sag to his knees, fighting to get his helmet off, and he leapt the stall.

Tried to leap the stall. Everything was wrong, and he landed heavily on a floor that seemed undecided about becoming a wall. He managed to get to his feet and was pulled sideways, dancing awkwardly across the stable to keep his balance.

The stables stretched and shrank like a picture in a distorting mirror. He'd gone to see some once in Ankh, the three of them hazarding a half-coin each to visit the transient marvels of Dr Mooner's Travelling Take Your Breath Away Emporium. But you knew then that it was only twisted glass that was giving you a head like a sausage and legs like footballs. Teppic wished he could be so certain that what was happening around him would allow of such a harmless explanation. You'd probably need a wobbly glass mirror to make it look normal.

He ran on taffy legs towards Ptraci and the high priest as the world was expanded and squeezed around him, and was momentarily gratified to see the girl squirm in Dios's grip and fetch him a tidy thump on the ear.

He moved as though in a dream, with the distances changing as though reality was an elastic thing. Another step sent him cannoning into the pair of them. He grabbed Ptraci's arm and staggered back to the camel stall, where the creature was still cudding and watching the scene with the nearest thing a camel will ever get to mild interest, and snatched its halter.

No-one seemed to be interested in stopping them as they helped each other through the doorway and out into the mad night.

'It helps if you shut your eyes,' said Ptraci.

Teppic tried it. It worked. A stretch of courtyard that his eyes told him was a quivering rectangle whose sides twanged like bowstrings became, well, just a courtyard under his feet.

'Gosh, that was clever,' he said. 'How did you think of that?'

'I always shut my eyes when I'm frightened,' said Ptraci.

'Good plan.'

'What's happening?'

'I don't know. I don't want to find out. I think going away from here could be an amazingly sensible idea. How do you make a camel kneel, did you say? I've got any amount of sharp things.'

The camel, who had a very adequate grasp of human language as it applied to threats, knelt down graciously. They scrambled aboard and the landscape lurched again as the beast jacked itself back on to its feet.

The camel knew perfectly well what was happening. Three stomachs and a digestive system like an industrial distillation plant gave you a lot of time for sitting and thinking.