K!sdra jumped back to avoid another thrust and fell full length on the turf. With a snarl Psepha unfolded his great wings and launched himself from his tree.

A moment later the wizard was standing over him, shouting, “Tell it that if it singes me I’ll let the sword go. I will. I’ll let it go! So tell it!”

The tip of the black sword was hovering over K!sdra’s throat, What was odd was that the wizard was obviously struggling with it, and it appeared to be singing to itself.

“Psepha!” K!sdra shouted.

The dragon roared in defiance, but pulled out of the dive that would have removed Rincewind’s head, and flapped ponderously back to the tree.

“Talk!” screamed Rincewind.

K!sdra squinted at him up the length of the sword.

“What would you like me to say?” he asked.

“What?”

“I said what would you like me to say?”

“Where are my friends? The barbarian and the little man is what I mean.”

“I expect they have been taken back to the Wyrmberg.”

Rincewind tugged desperately against the surge of the sword, trying to shut his mind to Kring’s bloodthirsty humming.

“The Wyrmberg. There is only one. It is Dragonhome.”

“And I suppose you were waiting to take me there, eh?”

K!sdra gulped involuntarily as the tip of the sword pricked a bead of blood from his adam’s apple.

“Don’t want people to know you’ve got dragons here, eh?” snarled Rincewind.

The dragonrider forgot himself enough to nod, and came within a quarter-inch of cutting his own throat.

Rincewind looked around desperately, and realized that this was something he was really going to have to go through with.

“Right then,” he said as diffidently as he could manage. “You’d better take me to this Wyrmberg of yours, hadn’t you?”

“I was supposed to take you in dead,” muttered K!sdra sullenly.

Rincewind looked down at him and grinned slowly. It was a wide, manic and utterly humourless rictus that was the sort of grin that is normally accompanied by small riverside birds wandering in and out picking scraps out of the teeth.

“Alive will do,” said Rincewind. “If we’re talking about anyone being dead, remember whose sword is in which hand.”

“If you kill me, nothing will prevent Psepha killing you,” shouted the prone dragonrider.

“So what I’ll do is, I’ll chop bits off,” agreed the wizard. He tried the effect of the grin again.

“Oh, all right,” said K!sdra sulkily. “Do you think I’ve got an imagination?”

He wriggled out from under the sword and waved at the dragon, which took wing again and glided in towards them. Rincewind swallowed.

“You mean we’ve got to go on that?” he said. K!sdra looked at him scornfully, the point of Kring still aimed at his neck.

“How else would anyone get to the Wyrmberg?”

“I don’t know,” said Rincewind. “How else?”

“I mean, there is no other way. It’s flying or nothing.”

Rincewind looked again at the dragon before him. He could quite clearly see through it to the crushed grass on which it lay but, when he gingerly touched a scale that was a mere golden sheen on thin air, it felt solid enough. Either dragons should exist completely or fail to exist at all, he felt. A dragon only half-existing was worse than the extremes.

“I didn’t know dragons could be seen through,” he said.

K!sdra shrugged. “Didn’t you?” he said.

He swung himself astride the dragon awkwardly because Rincewind was hanging on to his belt. Once uncomfortably aboard the wizard moved his white-knuckle grip to a convenient piece of harness and prodded K!sdra lightly with the sword.

“Have you ever flown before?” said the dragonrider, without looking round.

“Not as such, no.”

“Would you like something to suck?”

Rincewind gazed at the back of the man’s head, then dropped to the bag of red and yellow sweets that was being proffered.

“Is it necessary?” he asked.

“It is traditional,” said K!sdra. “Please yourself.”

The dragon stood up, lumbered heavily across the meadow, and fluttered into the air.

Rincewind occasionally had nightmares about teetering on some intangible but enormously high place, and seeing a blue-distanced, cloud-punctuated landscape reeling away below him (this usually woke him up with his ankles sweating; he would have been even more worried had he known that the nightmare was not, as he thought, just the usual discworld vertigo. It was a backwards memory of an event in his future so terrifying that it had generated harmonics of fear all the way along his lifeline).

This was not that event, but it was good practise for it. Psepha clawed its way into the air with a series of vertebrae-shattering bounds. At the top of its last leap the wide wings unfolded with a snap and spread out with a thump which shook the trees. Then the ground was gone, dropping away in a series of gentle jerks. Psepha was suddenly rising gracefully, the afternoon sunlight gleaming off wings that were still no more than a golden film. Rincewind made the mistake of glancing downwards, and found himself looking through the dragon to the treetops below. Far below. His stomach shrank at the sight.

Closing his eyes wasn’t much better, because it gave his imagination full rein. He compromised by gazing fixedly into the middle distance, where moorland and forest drifted by and could be contemplated almost casually.

Wind Snatched at him. K!sdra half turned and shouted into his ear.

“Behold the Wyrmberg!”

Rincewind turned his head slowly, taking care to keep Kring resting lightly on the dragon’s back. His streaming eyes saw the impossibly inverted mountain rearing out of the deep forested valley like a trumpet in a tub of nose. Even at this distance he could make out the faint octarine glow in the air that must be indicating a stable magic aura of at least - he gasped - several milliPrime? At least!

“Oh no,” he said.

Even looking at the ground was better than that. He averted his eyes quickly, and realized that he could now no longer see the ground through the dragon. As they glided around in a wide circle towards the Wyrmberg it was definitely taking on a more solid form, as if the creature’s body was filling with a gold mist. By the time the Wyrmberg was in front of them, swinging wildly across the sky, the dragon was as real as a rock.

Rincewind thought he could see a faint streak in the air, as if something from the mountain had reached out and touched the beast. He got the strange feeling that the dragon was being made more genuine.

Ahead of it the Wyrmberg turned from a distant toy to several billion tons of rock poised between heaven and earth. He could see small fields, woods and a lake up there, and from the lake a river spilled out and over the edge…

He made the mistake of following the thread of foaming water with his eyes, and jerked himself back just in time.

The flared plateau of the upturned mountain drifted towards them. The dragon didn’t even slow. As the mountain loomed over Rincewind like the biggest fly-swatter in the universe he saw a cave mouth. Psepha skimmed towards it, shoulder muscles pumping.

The wizard screamed as the dark spread and enfolded him. There was a brief vision of rock flashing past, blurred by speed. Then the dragon was in the open again.

It was inside a cave, but bigger than any cave had a right to be. The dragon, gliding across its vast emptiness, was a mere gilded fly in a banqueting hall.

There were other dragons -gold, silver, black, white -flapping across the sun-shafted air on errands of their own or perched on outcrops of rock. High in the domed roof of the cavern scores of others hung from huge rings, their wings wrapped bat-like around their bodies. There were men up there, too. Rincewind swallowed hard when he saw them, because they were walking on that broad expanse of ceiling like flies.

Then he made out the thousands of tiny rings that studded the ceiling. A number of inverted men were watching Psepha’s flight with interest. Rincewind swallowed again. For the life of him he couldn’t think of what to do next.

“Well?” he asked, in a whisper. “Any suggestions?

“Obviously you attack,” said Kring scornfully.

“Why didn’t I think of that?” said Rincewind

“Could it be because they all have crossbows?”

“You’re a defeatist.”

“Defeatist? That’s because I’m going to be defeated!”

“You’re your own worst enemy, Rincewind,” said the sword.

Rincewind looked up at grinning men.

“Bet?” he said wearily.

Before Kring could reply Psepha reared in midair and alighted on one of the large rings, which rocked alarmingly.

“Would you like to die now, or surrender first?” asked K!sdra calmly.

Men were converging on the ring from all directions, walking with a swaying motion as their hooked boots engaged the ceiling rings. There were more boots on a rack that hung in a small platform built on the side of the perch-ring. Before Rincewind could stop him the dragonrider had leapt from the creature’s back to land on the platform, where he stood grinning at the wizard’s discomfiture.

There was a small expressive sound made by a number of crossbows being cocked. Rincewind looked up at a number of impassive, upside down faces. The dragonfolk’s taste in clothing didn’t run to anything much more imaginative than a leather harness, studded with bronze ornaments. Knives and sword sheaths were worn inverted. Those who were not wearing helmets let their hair flow freely, so that it moved like seaweed in the ventilation breeze near the roof. There were several women among them. The inversion did strange things to their anatomy. Rincewind stared.

“Surrender,” said K!sdra again.

Rincewind opened his mouth to do so. Kring hummed a warning, and agonising waves of pain shot up his arm. “Never,” he squeaked. The pain stopped.

“Of course he won’t!” boomed an expansive voice behind him. “He’s a hero, isn’t he?”

Rincewind turned and looked into a pair of hairy nostrils. They belonged to a heavily built young man, hanging nonchalantly from the ceiling by his boots.

“What is your name, hero?” said the man. “so that we know who you were.”

Agony shot up Rincewind’s arm. “I-I’m Rincewind of Ankh,” he managed to gasp.

“And I am Lio!rt Dragonlord,” said the hanging man, pronouncing the word with the harsh click in the back of the throat that Rincewind could only think of as a kind of integral punctuation. “You have come to challenge me in mortal combat.”

“Well, no, I didn’t-“

“You are mistaken. K!sdra, help our hero into a pair of hookboots. I am sure he is anxious to get started.”

“No, look, I just came here to find my friends. I’m sure there’s no-” Rincewind began, as the dragonrider guided him firmly onto the platform, pushed him onto a seat, and proceeded to strap hookboots to his feet.

“Hurry up, K!sdra. We mustn’t keep our hero from his destiny,” said Lio!rt.

“Look, I expect my friends are happy enough here, so if you could just, you know, set me down somewhere