'Father, you've seen the way it soaks up. . . you've seen the frost . .

'Let it soak. We Ptaclusps don't go around capping off pyramids as though we were finishing off a garden wall. We don't knock off like a wossname in the night. People expect a ceremony.

'But-'

'I'm not listening. I've listened to too much of this new— fangled stuff. Tomorrow. I've had the bronze plaque made, and the velvet curtains and everything.'

One of the IIas shrugged. 'It's no good arguing with him,' he said. 'I'm from three hours ahead. I remember this meeting. We couldn't change his mind.'

'I'm from two hours ahead,' said one of his clones. 'I remember you saying that, too.'

Beyond the walls of the tent, the pyramid sizzled with accumulated time.

There is nothing mystical about the power of pyramids.

Pyramids are dams in the stream of time. Correctly shaped and orientated, with the proper paracosmic measurements correctly plumbed in, the temporal potential of the great mass of stone can be diverted to accelerate or reverse time over a very small area, in the same way that a hydraulic ram can be induced to pump water against the flow.

The original builders, who were of course ancients and therefore wise, knew this very well and the whole point of a correctly-built pyramid was to achieve absolute null time in the central chamber so that a dying king, tucked up there, would indeed live forever — or at least, never actually die. The time that should have passed in the chamber was stored in the bulk of the pyramid and allowed to flare off once every twenty-four hours.

After a few aeons people forgot this and thought you could achieve the same effect by a) ritual b) pickling people and c) storing their soft inner bits in jars.

This seldom works.

And so the art of pyramid tuning was lost, and all the knowledge became a handful of misunderstood rules and hazy recollections. The ancients were far too wise to build very big pyramids. They could cause very strange things, things that would make mere fluctuations in time look tiny by comparison.

By the way, contrary to popular opinion pyramids don't sharpen razor blades. They just take them back to when they weren't blunt. It's probably because of quantum.

Teppic lay on the strata of his bed, listening intently.

There were two guards outside the door, and another two on the balcony outside, and — he was impressed at Dios's forethought

— one on the roof. He could hear them trying to make no noise.

He'd hardly been able to protest. If black-clad miscreants were getting into the palace, then the person of the king had to be protected. It was undeniable.

He slipped off the solid mattress and glided through the twilight to the statue of Bast the Cat-Headed God in the corner, twisted off the head, and pulled out his assassin's costume. He dressed quickly, cursing the lack of mirrors, and then padded across and lurked behind a pillar.

The only problem, as far as he could see, was not laughing. Being a soldier in Djelibeybi was not a high risk job. There was never a hint of internal rebellion and, since either neighbour could crush the kingdom instantly by force of arms, there was no real point in selecting keen and belligerent warriors. In fact, the last thing the priesthood wanted was enthusiastic soldiers. Enthusiastic soldiers with no fighting to do soon get bored and start thinking dangerous thoughts, like how much better they could run the country.

Instead the job attracted big, solid men, the kind of men who could stand stock still for hours at a time without getting bored, men with the build of an ox and the mental processes to match. Excellent bladder control was also desirable.

He stepped out on to the balcony.

Teppic had learned how not to move stealthily. Millions of years of being eaten by creatures that know how to move stealthily has made humanity very good at spotting stealthy movement. Nor was it enough to make no noise, because little moving patches of silence always aroused suspicion. The trick was to glide through the night with a quiet reassurance, just like the air did.

There was a guard standing just outside the room. Teppic drifted past him and climbed carefully up the wall. It had been decorated with a complex bas relief of the triumphs of past monarchs, so Teppic used his family to give him a leg up.

The breeze was blowing off the desert as he swung his legs over the parapet and walked silently across the roof, which was still hot underfoot. The air had a recently-cooked smell, tinted with spice.

It was a strange feeling, to be creeping across the roof of your own palace, trying to avoid your own guards, engaged on a mission in direct contravention of your own decree and knowing that if you were caught you would have yourself thrown to the sacred crocodiles. After all, he'd apparently already instructed that he was to be shown no mercy if he was captured.

Somehow it added an extra thrill.

There was freedom of a sort up here on the rooftops, the only kind of freedom available to a king of the valley. It occurred to Teppic that the landless peasants down on the delta had more freedom than he did, although the seditious and non-kingly side of him said, yes, freedom to catch any diseases of their choice, starve as much as they wanted, and die of whatever dreadful ague took their fancy. But freedom, of a sort.

A faint noise in the huge silence of the night drew him to the riverward edge of the roof. The Djel sprawled in the moonlight, broad and oily.

There was a boat in midstream, heading back from the far bank and the necropolis. There was no mistaking the figure at the oars. The flarelight gleamed off his bald head.

One day, Teppic thought, I'll follow him. I'll find out what it is he does over there.

If he goes over in daylight, of course.

In daylight the necropolis was merely gloomy, as though the whole universe had shut down for early-closing. He'd even explored it, wandering through streets and alleys that contrived to be still and dusty no matter what the weather was on the other, the living side of the water. There was always a breathless feel about it, which was probably not to be wondered at. Assassins liked the night on general principles, but the night of the necropolis was something else. Or rather, it was the same thing, but a lot more of it. Besides, it was the only city anywhere on the Disc where an assassin couldn't find employment.

He reached the light well that opened on the embalmers' courtyard and peered down. A moment later he landed lightly on the floor and slipped into the room of cases.

'Hallo, lad.'

Teppic opened the lid of the case. It was still empty.

'She's in one of the ones at the back,' said the king. 'Never had much of a sense of direction.'

It was a great big palace. Teppic could barely find his way around it by daylight. He considered his chances of carrying out a search in pitch darkness.

'It's a family trait, you know. Your grandad had to have Left and Right painted on his sandals, it was that bad. It's lucky for you that you take after your mother in that respect.'

It was strange. She didn't talk, she chattered. She didn't seem to be able to hold a simple thought in her head for more than about ten seconds. Her brain appeared to be wired directly to her mouth, so that as soon as a thought entered her head she spoke it out loud. Compared to the ladies he had met at soirees in Ankh, who delighted in entertaining young assassins and fed them expensive delicacies and talked to them of high and delicate matters while their eyes sparkled like carborundum drills and their lips began to glisten compared to them, she was as empty as a, as a, well, as an empty thing. Nevertheless, he found he desperately wanted to find her. The sheer undemandingness of her was like a drug. The memory of her bosom was quite beside the point.

'I'm glad you've come back for her,' said the king vaguely.

'She's your sister, you know. Half sister, that is. Sometimes I wish I'd married her mother, but you see she wasn't royal. Very bright woman, her mother.'

Teppic listened hard. There it was again: a faint breathing noise, only heard at all because of the deep silence of the night. He worked his way to the back of the room, listened again, and lifted the lid of a case.

Ptraci was curled up on the bottom, fast asleep with her head on her arm.

He leaned the lid carefully against the wall and touched her hair. She muttered something in her sleep, and settled into a more comfortable position.

'Er, I think you'd better wake up,' he whispered.

She changed position again and muttered something like: 'Wstflgl.'

Teppic hesitated. Neither his tutors nor Dios had prepared him for this. He knew at least seventy different ways of killing a sleeping person, but none to wake them up first.

He prodded her in what looked like the least embarrassing area of her skin. She opened her eyes.

'Oh,' she said. 'It's you.' And she yawned.

'I've come to take you away,' said Teppic. 'You've been asleep all day.'

'I heard someone talking,' she said, stretching in a fashion that made Teppic look away hurriedly. 'It was that priest, the one with the face like a bald eagle. He's really horrible.'

'He is, isn't he?' agreed Teppic, intensely relieved to hear it said.

'So I just kept quiet. And there was the king. The new king.'

'Oh. He was down here, was he?' said Teppic weakly. The bitterness in her voice was like a Number Four stabbing knife in his heart.

'All the girls say he's really weird,' she added, as he helped her out of the case. 'You can touch me, you know. I'm not made of china.'

He steadied her arm, feeling in sore need of a cold bath and a quick run around the rooftops.

'You're an assassin, aren't you,' she went on. 'I remembered that after you'd gone. An assassin from foreign parts. All that black. Have you come to kill the king?'

'I wish I could,' said Teppic. 'He's really beginning to get on my nerves. Look, could you take your bangles off?'

'Why?'

'They make such a noise when you walk.' Even Ptraci's earrings appeared to chime the hours when she moved her head.

'I don't want to,' she said. 'I'd feel naked without them.'

'You're nearly naked with them,' hissed Teppic. 'Please!'

'She can play the dulcimer,' said the ghost of Teppicymon XXVII, apropos of nothing much. 'Not very well, mind you. She's up to page five of «Little Pieces for Tiny Fingers».'

Teppic crept to the passage leading out of the embalming room and listened hard. Silence ruled in the palace, broken only by heavy breathing and the occasional clink behind him as Ptraci stripped herself of her jewellery. He crept back.

'Please hurry up,' he said, 'we haven't got a lot of-'

Ptraci was crying.

'Er,' said Teppic. 'Er.'

'Some of these were presents from my granny,' sniffed Ptraci. 'The old king gave me some, too. These earrings have been in my family for ever such a long time. How would you like it if you had to do it?'

'You see, jewellery isn't just something she wears,' said the ghost of Teppicymon XXVII. 'It's part of who she is.' My word, he added to himself, that's probably an Insight. Why is it so much easier to think when you're dead?

'I don't wear any,' said Teppic.

'You've got all those daggers and things.'

'Well, I need them to do my job.'

'Well then.'

'Look, you don't have to leave them here, you can put them in my pouch,' he said. 'But we must be going. Please!'

'Goodbye,' said the ghost sadly, watching them sneak out to the courtyard. He floated back to his corpse, who wasn't the best of company.

The breeze was stronger when they reached the roof. It was hotter, too, and dry.

Across the river one or two of the older pyramids were already sending up their flares, but they were weak and looked wrong.

'I feel itchy,' said Ptraci. 'What's wrong?'

'It feels like we're in for a thunderstorm,' said Teppic, staring across the river at the Great Pyramid. Its blackness had intensified, so that it was a triangle of deeper darkness in the night. Figures were running around its base like lunatics watching their asylum burn.

'What's a thunderstorm?'

'Very hard to describe,' he said, in a preoccupied voice. 'Can you see what they're doing over there?'

Ptraci squinted across the river.

'They're very busy,' she said.

'Looks more like panic to me.'

A few more pyramids flared, but instead of roaring straight up the flames flickered and lashed backwards and forwards, driven by intangible winds.

Teppic shook himself. 'Come on,' he said. 'Let's get you away from here.'

'I said we should have capped it this evening,' shouted Ptaclusp IIb above the screaming of the pyramid. 'I can't float it up now, the turbulence up there must be terrific!'

The ice of day was boiling off the black marble, which was already warm to the touch. He stared distractedly at the capstone on its cradle and then at his brother, who was still in his nightshirt.

'Where's father?' he said.

'I sent one of us to go and wake him up,' said IIa.

'Who?'

'One of you, actually.'

'Oh.' IIb stared again at the capstone. 'It's not that heavy,' he said. 'Two of us could manhandle it up there.' He gave his brother an enquiring look.

'You must be mad. Send some of the men to do it.'

'They've all run away-'

Down river another pyramid tried to flare, spluttered, and then ejected a screaming, ragged flame that arched across the sky and grounded near the top of the Great Pyramid itself.

'It's interfering with the others now!' shouted IIb. 'Come on. We've got to flare it off, it's the only way!'

About a third of the way up the pyramid's flanks a crackling blue zigzag arced out and struck itself on a stone sphinx. The air above it boiled.

The two brothers slung the stone between them and staggered to the scaffolding, while the dust around them whirled into strange shapes.

'Can you hear something?' said IIb, as they stumbled on to the first platform.

'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.

It's not for nothing that advanced mathematics tends to be invented in hot countries. It's because of the morphic resonance of all the camels, who have that disdainful expression and famous curled lip as a natural result of an ability to do quadratic equations.

It's not generally realised that camels have a natural aptitude for advanced mathematics, particularly where they involve ballistics. This evolved as a survival trait, in the same way as a human's hand and eye co-ordination, a chameleon's camouflage and a dolphin's renowned ability to save drowning swimmers if there's any chance that biting them in half might be observed and commented upon adversely by other humans.

The fact is that camels are far more intelligent than dolphins19.

They are so much brighter that they soon realised that the most prudent thing any intelligent animal can do, if it would prefer its descendants not to spend a lot of time on a slab with electrodes clamped to their brains or sticking mines on the bottom of ships or being patronised rigid by zoologists, is to make bloody certain humans don't find out about it. So they long ago plumped for a lifestyle that, in return for a certain amount of porterage and being prodded with sticks, allowed them adequate food and grooming and the chance to spit in a human's eye and get away with it.

And this particular camel, the result of millions of years of selective evolution to produce a creature that could count the grains of sand it was walking over, and close its nostrils at will, and survive under the broiling sun for many days without water, was called You Bastard.

And he was, in fact, the greatest mathematician in the world.

You Bastard was thinking: there seems to be some growing dimensional instability here, swinging from zero to nearly forty— five degrees by the look of it. How interesting. I wonder what's causing it? Let V equal 3. Let Tau equal Chi/4. cudcudcud Let Kappa/y be an Evil-Smelling-Bugger20 differential tensor domain with four imaginary spin co-efficients…

Ptraci hit him across the head with her sandal. 'Come on, get a move on!' she yelled. You Bastard thought: Therefore H to the enabling power equals V/s. cudcudcud Thus in hypersyllogic notation . . .

Teppic looked behind him. The strange distortions in the landscape seemed to be settling down, and Dios was . . .

Dios was striding out of the palace, and had actually managed to find several guards whose fear of disobedience overcame the terror of the mysteriously distorted world.

You Bastard stood stoically chewing. . . cudcudcud which gives us an interesting shortening oscillation. What would be the period of this? Let period = x. cudcudcud Let t = time. Let initial period . . .

Ptraci bounced up and down on his neck and kicked hard with her heels, an action which would have caused any anthropoid male to howl and bang his head against the wall.

'It won't move! Can't you hit it?'

Teppic brought his hand down as hard as he could on You Bastard's hide, raising a cloud of dust and deadening every nerve in his fingers. It was like hitting a large sack full of coathangers.

'Come on,' he muttered.

Dios raised a hand.

'Halt, in the name of the king!' he shouted.

An arrow thudded into You Bastard's hump.

. . . equals 6.3 recurring. Reduce. That gives us ouch . . . 314 seconds . . .