‘I think it might have done. I’m sorry.’

‘Who were they?’ she asked.

‘I don’t know,’ Rory said, a little helplessly. ‘I didn’t know their names. We’d only just met. In the confusion, everybody scattered. I ran. Like you, I just ran. And it could have shot me too, but it didn’t. It just chased me.’

‘Like it wanted… to catch you?’

Rory nodded. His throbbing head reminded him what a bad idea that was, and he winced. ‘That had occurred to me,’ he said. ‘It’s not a nice thought. I have been wondering why. Anyway, I ran.’

‘And that’s how you ended up at the autumn mills?’

‘Where?’

She laughed. ‘Here! The autumn mills!’

‘OK. I didn’t know what they were called.’

Vesta’s long skirts were torn and dirty. She idly smoothed them out over her knees.

‘I came here because it was the closest place I could think of to hide in,’ she said. ‘I ran a long way just to get away from it. By the time I even thought about which way I was going, I realised I’d gone off opposite to where Beside was. I was a Cat A fool for doing that.

I got my bearings and figured that the autumn mills would be the best bet for a roof and shelter and warmth.’

‘Why is the water warm?’ Rory asked. ‘Even under the ice, there’s heat in it. I know because I fell through the ice.’

‘No wonder you look like a compost heap,’ said Vesta. She shrugged. ‘The water’s warm because it flows into the streams from the Firmer. These streams, it would be Firmer Number Two, actually. It’s a thermal exchange system. Guide teaches us that water is used in the Firmers for cooling, and then sent out, and the mills harvest the heat to store in the plantnation’s conservator reservoir. Light and wind and water, we borrow power from all. The mills take power autumnatically from the streams.’

‘How… how do they do it?’ asked Rory.

‘Autumnatically.’

‘Automatically?’

‘Say it proper! Autumnatically! Didn’t you get schooled where you were raised?’

‘A little.’

She peered at him, as if trying to read things in his face. Just having someone to talk to seemed to have perked her up, and reduced the trauma of what had clearly been an unpleasant day. Rory had seen that process work many times. A little chat, a chance to say things out loud.

‘What labour do you do, Rory?’ she asked. ‘Let me guess. Are you a shepherd?’

‘No.’

‘Then a plantsman. That’s it! A plantsman.’

‘No, actually I’m a nurse.’

Vesta gazed at him, bewildered. ‘A nurse? You’re a nurse?’

‘Yes.’

She leapt up, brushing her clothes down, her head bowed. ‘Oh my Guide! I am so ashamed! So ashamed of my comportment!’

‘Whoa, what?’ asked Rory, getting up.

‘You are an elect, an elect, and I show you no courtesy or respect! Oh goodness, and to think I struck you on the head too!’

‘Calm down. Please, calm down. It’s all right.’

She looked at him uneasily. ‘I didn’t know. Honest, and may Guide strike me down. I had no idea. You look too young, and you do not have a beard either.’

‘I can understand how you made the mistake,’ said Rory.

‘Were you coming to visit us at Beside?’

‘Yes,’ said Rory.

‘For the festival?’

‘The festival…?’ he asked.

‘The winter festival.’

‘Yes,’ said Rory firmly, nodding. ‘That’s why we’d come. To celebrate.’

‘You weren’t on your own then?’

‘What?’

‘You said “we”,’ said Vesta.

‘I did, didn’t I?’

‘Obviously someone as important as the Nurse Elect of a plantnation wouldn’t travel alone. That would make no sense.’

‘It wouldn’t, would it?’ asked Rory.

‘So where is the rest of your party?’

‘It was just a small group. Three of us… travelling from, um, afar,’ said Rory. ‘The Doctor and… another person. We got lost and separated.’

‘How terrible, Elect,’ she said. ‘I hope they are all right.’

‘So do I,’ Rory agreed.

‘We used to have wellwishers every year for the festival, but not since the winters turned white. The Morphans of Beside will be overjoyed that you have made this effort for the festival. We should go. We should go at once.’

‘To Beside? Now?’

‘Yes,’ said Vesta. She was very earnest. ‘This mill is quite secure, I suppose, but I do not wish to spend the night here, not with it out there. It is late, and it is cold, but if we go together and walk with purpose, we might make it in an hour.’

‘OK,’ said Rory. ‘What about my friends?’

‘We must hope Guide watches out for them,’ said Vesta.

The Ice Warriors moved surprisingly fast for such big creatures. They weren’t running, but their stride rate had increased. They pursued the Doctor and his companions out of the tree-line and onto the soft snow dunes of the open grazing. Their gait was powerful and sure-footed even on the softest snow, as though they were evolved to excel in such conditions. It felt as if they could stride for ever, and knock down anything that got in their way, and no matter how fast you fled, eventually they’d catch up with you when you collapsed of exhaustion.

“This way!’ Samewell shouted, running ahead into the open ground. Lazy snowflakes billowed around him, spilling from a sky as dark as wet granite. ‘Come on!’

‘No! No! No!’ the Doctor yelled. He was still fiddling with his sonic screwdriver as he ran. ‘Not that way! Keep to the trees!’

Samewell was not going to be deterred, and Arabel was following him closely. Either he knew what he was doing, or he’d entirely taken leave of his senses, especially the one relating to direction. Given that surprise had almost sent Samewell running towards the Ice Warriors when they first appeared, the Doctor was not filled with confidence.

The sonic screwdriver started chirruping again. He aimed it at the Ice Warriors, neutralising the lethal blasts of their sonic weapons, and bounded on after the others.

Samewell had led them towards some kind of gully.

He did know what he was doing after all.

There were some steep ditches and sunken stream beds in the slopes between the wood and the gently rising Moreland. Snow-cover had softened them into narrow channels and defiles, blended invisibly into the whiteness. Amy and the Doctor found themselves slithering down a deep bank behind Arabel and Samewell, and then slogging along a winding channel out of view of the edge of the wood. There were a few lonely trees and coarse bushes, coated in snow, and large snow-dusted boulders jutted out of the frozen stream bed.

Arabel slipped and half-fell, but Amy grabbed her and pulled her up again. They kept running.

The Doctor’s screwdriver didn’t. It puttered out again. They could hear the Ice Warriors descending the bank behind them, but they couldn’t see them.

Samewell led the fugitives along another channel, and then through a gentle basin where a lip of rock crowned with a gnarled tree overhung. Hard snow, driven by the wind across Moreland, blew down into their faces like sleet.

Samewell gestured urgently for them to keep following him. He scrambled up another bank, cascading powder snow in all directions, and led them back onto a raised stretch of the grazing.

There was a hut ahead of them. It was quite small, round, with a conical roof. Snow had drifted against its northward face. It was the shelter Samewell had told them about. It was the vent.

The Doctor felt an acute rush of pity. Samewell had been trying so hard. His solution to them being lost out in the snow was to lead them to the vent. His solution to them being chased by murderous Ice Warriors was the same plan, unmodified. A vent provided shelter and safety for a herder. That was the way Samewell’s mind worked.

As they got closer, the Doctor rapidly revised his opinion. The vent was made of metal. The entire structure was composed out of shipskin. If they could bar the door, it might indeed protect against Ice Warriors.