Crimm nodded. Though he must have known what a burden this would be for a folk already on the edge of starvation, Avatak thought, he seemed enthused. ‘We will do this, Uncle. We are Northlanders; this is Etxelur. This is what we are for. And then our children, and our children’s children, will stand guard on the Wall until the day the warmth returns to the world.’

Pyxeas sighed. ‘Brave words, Crimm. But it’s impossible, I’m afraid. I told you – the ice will see to it.’

And he spoke to them of what was to come.

‘The snow will continue to fall, and none of it will melt. It will gather deeper and deeper, the lower layers compressing to hard ice. At last, around centres to the north of Albia, in Scand, in Asia, in the Land of the Sky Wolf, huge sheets will accumulate. How do I know this? Because this is how it was before. I have seen the marks of it. And this ocean, this ancient land, even the Wall itself, will be entirely covered over, with a great thickness of ice – as thick as a day’s walk! And so you must leave here. Go south, to the edge of the ice. Find a new place to live. For this land is doomed.

‘But the Wall will survive. The growstone core is tough enough for that. Riding out the years, resisting the ice as it has already resisted the ocean for millennia. And in its growstone carcass, to be discovered anew by the children of a distant future, will be the secrets of the world. Those children will begin knowing as much as we know now. Who knows what they will go on to learn? And you will leave them your drawings too, Nelo. Let them look upon the faces of their ancestors.’

This was met by silence, save from the gurgle of a baby somewhere.

Crimm waved a hand at the growstone village, the sea. ‘You speak of generations yet unborn. We have survived. We are proud of what we have built here. Must we lose it all?’

‘It is already lost,’ Pyxeas said gently. ‘The land is only ever loaned from the ice; now the ice takes it back. But next time, next time . . .’

‘Crimm! Aranx!’

The call came from the west, along the growstone shore. People stood, peered into the sun, hands over their eyes. Crimm waved. ‘I’m here! Ayto, is that you?’

‘We found an animal,’ Ayto called, his cry distant, small. ‘A big one. A bear! White, or yellow.’

Crimm was baffled. ‘A white bear?’

Avatak was already on his feet. ‘Nanok. I knew he would come.’

Crimm grinned, took a spear from a pile, threw it to Avatak. ‘After you.’