Nona shook free and wordlessly scrambled away from the shipheart, its fire burning in her blood.

‘Do you think that in all the vastness of the ice there are no more of these?’ Zole jerked her head back towards her pack. ‘None of your “shiphearts”? You think they exist only in this narrow strip of Abeth where green things still grow?’

‘Well …’ Nona hadn’t really thought about it. ‘But the ice covers …’

‘There are ways down. And the ice-tribes are the descendants of those who refused to run before its advance, peoples who walked the green face of Abeth thousands of years ago. They took their treasures up onto the ice with them.’

Zole moved on and for what seemed an age it was all Nona could do to keep up with her. The ice-triber stopped where a trickle of freezing water spilled from a crack in the rocks. ‘Drink.’ She began to fill her waterskin.

Nona found a still smaller trickle spilling from an overhang and stood with her mouth open to receive it. After a few gulps she stepped away. ‘You have a devil in you, one of those … did you call them klaulathu?’

‘You had a klaulathu under your skin, Nona Grey, an echo of the Missing. This,’ she opened her hand and the palm lay scarlet, ‘is a raulathu, it is not of the Missing. It is an echo of me.’

‘I don’t understand.’

Zole narrowed her eyes, looking past Nona, up at the slopes above her. ‘The clouds did not slow them as much as I had hoped. They have found us again.’ She turned and dropped away, landing on a huge boulder twenty feet below the ledge that Nona’s stream trickled over.

Nona peered over the drop. ‘Damn.’ She glanced up at the dark spots moving on the higher slopes. With a shrug she gathered her aching body into a focused knot, stepped out into space, and let the fall have her.

They left the clouds behind them, clinging to the mountains’ shoulders, and early sunshine welcomed the two novices into the eastern foothills. Nothing dared the rugged terrain save a few varieties of wire-grass and the goats that pursued them up from the plains. Zole led the way although she had no better idea of the geography than Nona, both of them relying on memories of Sister Rule’s endless maps. They moved quickly, following streams down into the valleys, alert for any herders checking on their flocks.

‘It could be the empire,’ Zole said. ‘It looks no different from the other side.’

‘A couple of centuries ago it was the empire.’

‘Perhaps the people will not be so different either, for all that Sister Wheel calls them eaters of children and deviants.’ Zole veered up towards the crest of the valley.

‘Maybe.’ Nona felt it hard to shake off the expectations built by a hundred fireside tales so easily. She fixed her eyes on Zole’s back and forced unwilling legs to match the girl’s pace down the slope. Sherzal’s soldiers appeared to have given up the chase, not prepared to venture onto Scithrowl territory. Of the Noi-Guin there was no sign, but Nona doubted that they would relent so easily. Even if their shipheart weren’t at stake.

‘This devil of yours …’ Nona returned to the conversation abandoned on the rock-faces far above them.

‘A raulathu.’

‘It’s some part of you that the shipheart has … broken off?’

‘An impurity of the spirit. In this state it can be purged, leaving a person closer to the divine.’

‘And.’ Nona paused to clamber over a shoulder of rock. ‘And you’ve touched a shipheart before? On the ice?’

‘My tribe calls them klauklar affac, “the footsteps of the Missing”. Most on the ice know them more simply as “Old Stones”. And yes, I have touched such a thing before. Two such things, in fact. When the ice-speakers find a child that can approach the Old Stones they test them. Each new raulathu takes longer to split from a person than the one before and is more difficult to purge. I gave twelve to the fire. It was hard to do. Neither of the tribe’s stones could find more.’

‘How old were you?’ Nona knew that when Zole described a thing as ‘hard’ it meant that anyone else would have been killed by it.

‘Nine. The ice-speaker banished me to the Corridor. He did not say why. My uncle took me to the empire margins. I was sold to Sherzal’s agent in a village called Shard.’

‘Do you … do you think that’s why you have no threads?

Zole made no answer. She had reached the ridge from where she could look down into the next valley and away towards the fortress to the north, the closest in the chain. ‘It seems that the Battle-Queen has ears in Sherzal’s palace, and swift access to them.’

Nona scrambled up to join Zole on the ridge. She straightened, wiping the grit from her palms. ‘Oh.’

A column of riders was spilling down the far side of the valley, a skirmish band on the shaggy ponies that dwelt wild in the region and could run all day over such terrain.

‘Sixty.’ Zole turned and dropped back below the ridge.

‘We can’t outrun them.’ Nona wasn’t sure she could outrun a three-legged mule right then.

Zole narrowed her eyes. A momentary frown and she was moving, back down into the valley again, angling towards their original path tracking the stream. On this side of the Grampains the rivers ran their course a while before vanishing beneath the ice sheets. On Sister Rule’s globe you could reverse the glaciers’ advance and set your fingers to ancient oceans picked out in blue enamel. Nona imagined they still lay there under miles of ice and that the sun-warmed waters of the Corridor must eventually reach those hidden seas.

‘If we’re going to fight we should do it here,’ Nona called after Zole.

‘Sixty is too many,’ Zole called back. ‘And more will come. I would rather rest.’

Nona shrugged and followed. Sixty was too many, and rest sounded good.

8

Holy Class

Present Day

Total darkness. An enduring silence wrapped Path Tower’s Third Room.

‘Dead dog’s bollocks!’ Nona broke the silence, banging her shin into something hard. The curse was one of Regol’s favourites, though he only used it when he thought she wasn’t there. One day Nona hoped to delight Clera with it.

She bent to rub her leg then reached out to examine the obstacle. A barrel-lidded casket. She wasn’t sure if she’d seen it in the moment before the light died or imagined it after. Her fingers explored the metal banding and found a heavy lock. Would there be more troublesome protections? Thread-traps? Sigil marks? Or did Sister Pan consider the fact that it rested in the third chamber of Path Tower sufficient defence?

Nona sat on the cold stone floor. She could put a foot to the Path and summon light but how that might end, so soon after the strange paths she had just pursued, Nona didn’t know and didn’t want to find out.

The lock was a big piece of cold iron. Nona defocused her sight to bring the thread-scape into view. The lock blazed with them. Threads for the metal itself, leading back through the journey from the locksmith’s, through the workshop, splitting through the smithies where various parts were beaten into shape, re-joining in the white heat of the forge, tracking back along rivers to the distant quarry that the ore had been dug from. All of them tangled with the lives of those who laboured to make the lock, and tangled with the old song of the earth where the iron’s constituents had lain for years uncounted.