‘They were unguidely, and they brought conjury with them,’ she replied.

‘I understand that,’ he said. ‘I do. But just because something is unguidely, just because it is not part of Guide’s law, it doesn’t mean we can ignore it. It could be killing us, Winnowner. Do we let it?’

‘Of course not,’ she said. ‘Survival is the greatest doctrine of all. What is happening to us may be exceptional, and therefore not covered in specifics in Guide’s words, but Guide will not fail us. We must look again. Study the passages. Guide will instruct us in ways we have not yet imagined.’

Bill Groan nodded. ‘I think so too. We should start again tonight. All night, if it takes it.’

‘Agreed,’ said Winnowner. ‘We will go in and you will say some words of consolation and comfort. Then I will open the Incrypt, and we will withdraw with the council for study.’

Chaunce Plowrite held the door for them and they entered the assembly. It was crowded. Almost every Morphan had come out, except those on nightwatch or with evening labours to perform.

Or those already lost, Bill Groan thought.

There was a hum of chatter in the room, but it died away as they came in and joined the other members of the council to take their seats. Small and very obvious knots of agitation surrounded the families of the missing men.

‘What will you do, Elect?’ Ela Seed asked, standing up almost at once. Her voice was clear and loud, but strained with worry. Her husband, Dom Seed, was one of the men who had not been seen since Guide’s Bell had chimed middle-morning.

‘I will ask Guide for direction, Ela,’ said Bill Groan.

‘Is that not what we have been doing for weeks now?’ asked Lane Cutter. Several of the Morphans around her uttered a rumble of support.

‘It is,’ said Bill.

‘And what good has it done?’ Lane asked, her face severe.

‘Such talk is verging on the unguidely, Lane,’ said Chaunce Plowrite. ‘I know you are most concerned at Hud’s absence, but—’

‘Unguidely, am I now?’ asked Lane with a brittle laugh. ‘I think Guide has deserted us.’

There was a flurry of talk, some of it dismayed.

‘I agree,’ said Ela Seed. ‘I know we must trust in Guide, and I know patience is our greatest virtue, and I know that those who are patient will provide for all of the plantnation, but we cannot just wait by for this to overcome us. My husband…’

Her voice broke. Her sister rose to steady her.

‘We will consult Guide’s words tonight,’ said Bill.

‘Winnowner is going directly to open the Incrypt.

We will not rest until we have searched every passage and every section for truth and pertinence.’

‘It is either that,’ Jack Duggat scoffed, ‘or we wait for a miracle!’

Laughter, little of it warm, rolled around the assembly.

‘I think a miracle is what we might have found,’ said Sol Farrow, speaking from the back of the hall.

Everyone turned. He had just come in, bringing snow with him.

‘A small one, at any rate,’ he said, ‘but it gives us hope.’

He turned and beckoned. Two people came in out of the night.

‘Oh good Guide,’ murmured Bill Groan. ‘Vesta Flurrish?’

‘I found her coming in from the edge of the woods, Elect,’ said Sol.

‘I am unhurt, Elect,’ Vesta said. Her cold cheeks had flushed in the heat of the assembly room. She indicated the man next to her. ‘This is Rory,’ she said.

‘Um, hello,’ said Rory.

The Doctor picked up one of the dead rats by the tail and peered at it. It was heavy, and it swung slightly in his grip. ‘Nasty,’ he remarked. ‘And purpose built.’

‘What?’ asked Amy. Her hearing was returning, but the world was still sounding muffled. ‘Did you say purpose built?’

‘Manufactured,’ the Doctor said. He reached in and peeled back the dead rat’s lips to reveal its metal teeth.

‘It’s a rat,’ he said. ‘Definitely a rat. Genetically, a rat.

From Earth. But it’s been modified. Customised.

Enhanced. And on an industrial scale, given the numbers of them.’

‘It hasn’t got eyes,’ said Amy.

‘No, because the designers didn’t think it needed them. These are sophisticated motion sensors.’ He pointed to the foam-like filler that packed the area where an ordinary rat would have had eyes.

‘Motion?’

‘In space, particularly interstellar space, it’s cold and often very, very dark. So motion is a much more sensible format to base your sensory function on.

There are some fairly advanced acoustic sensors there too.’

‘Wait,’ said Amy, shaking her head and frowning.

She knew it wasn’t possible and she knew it wouldn’t do any good, but she really wanted a cotton bud. Her ears felt like they were gummed up with glue. ‘Start again. We’re not in space.’

‘No,’ agreed the Doctor, lifting his arm so he could study the suspended rat from below. ‘We’re in the terraformer. That’s one of the very big machines that the original Morphans constructed to change Hereafter from Earth -esque to properly Earth -like!

‘You mean the Firmers?’ asked Arabel. ‘The Terra Firmers?’

‘The three mountains that aren’t mountains?’ asked Amy.

The Doctor smiled and nodded. ‘Yes,’ he said. ‘I think we’re in Firmer Number Two, if I’ve been listening to Arabel correctly and my sense of direction is unerring.’ He looked at Amy. ‘And it is,’ he grinned.

‘We’re underneath the mountain?’ asked Samewell.

‘This is what a Firmer looks like inside. Well, part of it.’

‘And that factory noise?’ asked Amy.

‘The vast engines of the Firmer at work,’ said the Doctor. ‘Atmospheric processors, geo-seismic actuators, meteorological generators, seeding pumps.

It’s a world factory. It’s changing the world. And it’s been doing it for twenty-seven generations. It’s an extraordinary piece of large-scale engineering performing an even more extraordinary and even more mind-bogglingly large-scale piece of engineering.’

‘So returning to my original question,’ said Amy, pointing. ‘“Blind space rats? Huh?’”

‘Transrats is a better term,’ said the Doctor. ‘Like Transhumans. Re-engineering both genetically and biologically to be more rat than rat. A living tool, if you like.’

‘I’ve met more than one of those,’ said Amy.

‘During the great Diaspora Era,’ said the Doctor,

‘when mankind was spreading out from Earth, they were quite common on bulk generation starships or hibernation arks. Those vessels are huge, like small countries in space. And they travelled for many lifetimes to reach their destinations. The human passengers would spend thousands of years in suspended animation, ready to wake when they arrived at their final colonial destination, or else they would live out lives during the travel time. Whole civilisations could rise and fall on a generation starship in the time it took to reach another star.’

‘Seriously?’ asked Amy.

The Doctor nodded. ‘And eco-systems would develop in the ship interiors in the meantime. Pests, lice, dirt, rodents. Mankind quickly learned that the best way to keep a generation starship clean was to keep them purged. Rats eat anything. So mankind engineered rats that could survive in almost any conditions and could eat anything. Transrats lived in the dark corners of the ships, basically eating anything that wasn’t supposed to be there.’

‘So… these came here on the Morphans’ original ship?’ asked Amy.

‘Well, yes and no,’ said the Doctor. ‘The idea of them did, the technology. But they wouldn’t have lasted for twenty-seven generations. They’re not immortal, and they don’t breed. These were manufactured recently.’

‘Meaning?’

The Doctor exhaled thoughtfully. ‘Meaning there’s an automated manufacturing plant for this kind of thing here somewhere, and also a genetic stockpile containing rat DNA that it could access in order to breed new rats for conversion.’