This is the bright candlelit room where the life-timers are stored – shelf upon shelf of them, squat hourglasses, one for every living person, pouring their fine sand from the future into the past. The accumulated hiss of the falling grains makes the room roar like the sea.

This is the owner of the room, stalking through it with a preoccupied air. His name is Death.

But not any Death. This is the Death whose particular sphere of operations is, well, not a sphere at all, but the Discworld, which is flat and rides on the back of four giant elephants who stand on the shell of the enormous star turtle Great A'Tuin, and which is bounded by a waterfall that cascades endlessly into space.

Scientists have calculated that the chance of anything so patently absurd actually existing are millions to one.

But magicians have calculated that million-to-one chances crop up nine times out of ten.

Death clicks across the black and white tiled floor on toes of bone, muttering inside his cowl as his skeletal fingers count along the rows of busy hourglasses.

Finally he finds one that seems to satisfy him, lifts it carefully from its shelf and carries it across to the nearest candle. He holds it so that the light lints off it, and stares at the little point of reflected brilliance.

The steady gaze from those twinkling eye-sockets encompasses the world turtle, sculling through the deeps of space, carapace scarred by comets and pitted by meteors. One day even Great A'Tuin will die, Death knows; now, that would be a challenge.

But the focus of his gaze dives onwards towards the blue-green magnificence of the Disc itself, turning slowly under its tiny orbiting sun.

Now it curves away towards the great mountain range called the Ramtops. The Ramtops are full of deep valleys and unexpected crags and considerably more geography than they know what to do with. They have their own peculiar weather, full of shrapnel rain and whiplash winds and permanent thunder-storms. Some people say it's all because the Ramtops are the home of old, wild magic. Mind you, some people will say anything.

Death blinks, adjusts for depth of vision. Now he sees the grassy country on the turnwise slopes of the mountains.

Now he sees a particular hillside.

Now he sees a field.

Now he sees a boy, running.

Now he watches.

Now, in a voice like lead slabs being dropped on granite, he says: YES.

There was no doubt that there was something magical in the soil of that hilly, broken area which – because of the strange tint that it gave to the local flora – was known as the octarine grass country. For example, it was one of the few places on the Disc where plants produced reannual varieties.

Reannuals are plants that grow backwards in time. You sow the seed this year and they grow last year.

Mort's family specialised in distilling the wine from reannual grapes. These were very powerful and much sought after by fortune-tellers, since of course they enabled them to see the future. The only snag was that you got the hangover the morning before, and had to drink a lot to get over it.

Reannual growers tended to be big, serious men, much given to introspection and close examination of the calendar. A farmer who neglects to sow ordinary seeds only loses the crop, whereas anyone who forgets to sow seeds of a crop that has already been harvested twelve months before risks disturbing the entire fabric of causality, not to mention acute embarrassment.

It was also acutely embarrassing to Mort's family that the youngest son was not at all serious and had about the same talent for horticulture that you would find in a dead starfish. It wasn't that he was unhelpful, but he had the land of vague, cheerful helpfulness that serious men soon learn to dread. There was something infectious, possibly even fatal, about it. He was tall, red-haired and freckled, with the sort of body that seems to be only marginally under its owner's control; it appeared to have been built out of knees.

On this particular day it was hurtling across the high fields, waving its hands and yelling.

Mort's father and uncle watched it disconsolately from the stone wall.

'What I don't understand,' said father Lezek, 'is that the birds don't even fly away. I'd fly away, if I saw it coining towards me.'

'Ah. The human body's a wonderful thing. I mean, his legs go all over the place but there's a fair turn of speed there.'

Mort reached the end of a furrow. An overfull woodpigeon lurched slowly out of his way.

'His heart's in the right place, mind,' said Lezek, carefully.

'Ah. 'Course, 'tis the rest of him that isn't.'

'He's clean about the house. Doesn't eat much,' said Lezek.

'No, I can see that.'

Lezek looked sideways at his brother, who was staring fixedly at the sky.

'I did hear you'd got a place going up at your farm, Hamesh,' he said.

'Ah. Got an apprentice in, didn't I?'

'Ah,' said Lezek gloomily, 'when was that, then?'

'Yesterday,' said his brother, lying with rattlesnake speed. 'All signed and sealed. Sorry. Look, I got nothing against young Mort, see, he's as nice a boy as you could wish to meet, it's just that —'

'I know, I know,' said Lezek. 'He couldn't find his arse with both hands.'

They stared at the distant figure. It had fallen over. Some pigeons had waddled over to inspect it.

'He's not stupid, mind,' said Hamesh. 'Not what you'd call stupid.'

'There's a brain there all right,' Lezek conceded. 'Sometimes he starts thinking so hard you has to hit him round the head to get his attention. His granny taught him to read, see. I reckon it overheated his mind.'

Mort had got up and tripped over his robe.

'You ought to set him to a trade,' said Hamesh, reflectively. 'The priesthood, maybe. Or wizardry. They do a lot of reading, wizards.'

They looked at each other. Into both their minds stole an inkling of what Mort might be capable of if he got his well-meaning hands on a book of magic.

'All right,' said Hamesh hurriedly. 'Something else, then. There must be lots of things he could turn his hand to.'

'He starts thinking too much, that's the trouble,' said Lezek. 'Look at him now. You don't think about how to scare birds, you just does it. A normal boy, I mean.'

Hamesh scratched his chin thoughtfully.

'It could be someone else's problem,' he said.

Lezek's expression did not alter, but there was a subtle change around his eyes.

'How do you mean?' he said.

'There's the hiring fair at Sheepridge next week. You set him as a prentice, see, and his new master'll have the job of knocking him into shape. 'Tis the law. Get him indentured, and 'tis binding.'

Lezek looked across the field at his son, who was examining a rock.

'I wouldn't want anything to happen to him, mind,' he said doubtfully. 'We're quite fond of him, his mother and me. You get used to people.'

'It'd be for his own good, you'll see. Make a man of him.'

'Ah. Well. There's certainly plenty of raw material,' sighed Lezek.

Mort was getting interested in the rock. It had curly shells in it, relics of the early days of the world when the Creator had made creatures out of stone, no-one knew why.

Mort was interested in lots of things. Why people's teeth fitted together so neatly, for example. He'd given that one a lot of thought. Then there was the puzzle of why the sun came out during the day, instead of at night when the light would come in useful. He knew the standard explanation, which somehow didn't seem satisfying.

In short, Mort was one of those people who are more dangerous than a bag full of rattlesnakes. He was determined to discover the underlying logic behind the universe.

Which was going to be hard, because there wasn't one. The Creator had a lot of remarkably good ideas when he put the world together, but making it understandable hadn't been one of them.

Tragic heroes always moan when the gods take an interest in them, but it's the people the gods ignore who get the really tough deals.

His father was yelling at him, as usual. Mort threw the rock at a pigeon, which was almost too full to lurch out of the way, and wandered back across the field.

And that was why Mort and his father walked down through the mountains into Sheepridge on Hogswatch Eve, with Mort's rather sparse possessions in a sack on the back of a donkey. The town wasn't much more than four sides to a cobbled square, lined with shops that provided all the service industry of the farming community.

After five minutes Mort came out of the tailors wearing a loose fitting brown garment of imprecise function, which had been understandably unclaimed by a previous owner and had plenty of room for him to grow, on the assumption that he would grow into a nineteen-legged elephant.

His father regarded him critically.

'Very nice,' he said, 'for the money.'

'It itches,' said Mort. 'I think there's things in here with me.'

There's thousands of lads in the world'd be very thankful for a nice warm —' Lezek paused, and gave up – 'garment like that, my lad.'

'I could share it with them?' Mort said hopefully.

'You've got to look smart,' said Lezek severely. 'You've got to make an impression, stand out in the crowd.'

There was no doubt about it. He would. They set out among the throng crowding the square, each listening to his own thoughts. Usually Mort enjoyed visiting the town, with its cosmopolitan atmosphere and strange dialects from villages as far away as five, even ten miles, but this time he felt unpleasantly apprehensive, as if he could remember something that hadn't happened yet.

The fair seemed to work like this: men looking for work stood in ragged lines in the centre of the square. Many of them sported little symbols in their hats to tell the world the kind of work they were trained in – shepherds wore a wisp of wool, carters a hank of horsehair, interior decorators a strip of rather interesting hessian wallcovering, and so on.

The boys seeking apprenticeships were clustered on the Hub side of the square.

'You just go and stand there, and someone comes and offers you an apprenticeship,' said Lezek, his voice trimmed with uncertainty. 'If they like the look of you, that is.'

'How do they do that?' said Mort.

'Well,' said Lezek, and paused. Hamesh hadn't explained about this bit. He drew on his limited knowledge of the marketplace, which was restricted to livestock sales, and ventured, 'I suppose they count your teeth and that. And make sure you don't wheeze and your feet are all right. I shouldn't let on about the reading, it unsettles people.'

'And then what?' said Mort.

'Then you go and learn a trade,' said Lezek.

'What trade in particular?'

'Well . . . carpentry is a good one,' Lezek hazarded. 'Or thievery. Someone's got to do it.'

Mort looked at his feet. He was a dutiful son, when he remembered, and if being an apprentice was what was expected of him then he was determined to be a good one. Carpentry didn't sound very promising, though – wood had a stubborn life of its own, and a tendency to split. And official thieves were rare in the Ramtops, where people weren't rich enough to afford them.

'All right,' he said eventually, 'I'll go and give it a try. But what happens if I don't get prenticed?'

Lezek scratched his head.

'I don't know,' he said. 'I expect you just wait until the end of the fair. At midnight. I suppose.'

And now midnight approached.

A light frost began to crisp the cobblestones. In the ornamental clock tower that overlooked the square a couple of delicately-carved little automatons whirred out of trapdoors in the clockface and struck the quarter hour.

Fifteen minutes to midnight. Mort shivered, but the crimson fires of shame and stubbornness flared up inside him, hotter than the slopes of Hell. He blew on his fingers for something to do and stared up at the freezing sky, trying to avoid the stares of the few stragglers among what remained of the fair.