Guards! Guards! (Discworld 8)

' 'I know. It should have torn its wings off and left a bloody great hole in the ground,“ said Lady Ramkin firmly. ”You can't muck about with aerodynamics. You can't just scale up from small to big and leave it at that, you see. It's all a matter of muscle power and lifting surfaces."

“I knew there was something wrong,” said Vimes, brightening up. “And the flame, too. Nothing goes around with that kind of heat inside it. How do swamp dragons manage it?”

“Oh, that's just chemicals,” said Lady Ramkin dismissively. “They just distill something flammable from whatever they’ve eaten and ignite the flame just as it comes out of the ducts. They never actually have fire inside them, unless they get a case of blowback.” “What happens then?”

“You're scraping dragon off the scenery,” said Lady Ramkin cheerfully. “I'm afraid they're not very well-designed creatures, dragons.” Vimes listened.

They would never have survived at all except that their home swamps were isolated and short of predators. Not that a dragon made good eating, anyway-once you'd taken away the leathery skin and the enormous flight muscles, what was left must have been like biting into a badly-run chemical factory. No wonder dragons were always ill. They relied on permanent stomach trouble for supplies of fuel. Most of their brain power was taken up with controlling the complexities of then- digestion, which could distill flame-producing fuels from the most unlikely ingredients. They could even rearrange their internal plumbing overnight to deal with difficult processes. They lived on a chemical knife-edge the whole time. One misplaced hiccup and they were geography.

And when it came to choosing nesting sites, the females had all the common sense and mothering instinct of a brick.

Vimes wondered why people had been so worried about dragons in the olden days. If there was one in a cave near you, all you had to do was wait until it self-ignited, blew itself up, or died of acute indigestion.

“You've really studied them, haven't you,” he said.

“Someone ought to.”

“But what about the big ones?”

“Golly, yes. They're a great mystery, you know,” she said, her expression becoming extremely serious.

“Yes, you said.”

“There are legends, you know. It seems as though one species of dragon started to get bigger and bigger and then . . . just vanished.”

“Died out, you mean?”

“No . . . they turned up, sometimes. From somewhere. Full of vim and vigour. And then, one day, they stopped coming at all.” She gave Vimes a triumphant look. “I think they found somewhere where they could really be. ”

“Really be what?”

“Dragons. Where they could really fulfil their potential. Some other dimension or something. Where the gravity isn't so strong, or something.”

“I thought when I saw it,” said Vimes, “I thought, you can't have something that flies and has scales like that.”

They looked at each other.

“We've got to find it in its lair,” said Lady Ramkin.

“No bloody flying newt sets fire to my city,” said Vimes.

“Just think of the contribution to dragon lore,” said Lady Ramkin.

“Listen, if anyone ever sets fire to this city, it's going to be me. ”

“It's an amazing opportunity. There's so many questions ...”

“You're right there.” A phrase of Carrot's crossed Vimes's mind. “It can help us with our enquiries,” he suggested.

“But in the morning,” said Lady Ramkin firmly.

Vimes's look of bitter determination faded.

“I shall sleep downstairs, in the kitchen,” said Lady Ramkin cheerfully. “I usually have a camp bed made up down there when it's egg-laying time. Some of the females always need assistance. Don't you worry about me.”

“You're being very helpful,” Vimes muttered.

“I've sent Nobby down to the city to help the others set up your headquarters,” said Lady Ramkin.