Nish stared at her shapely bottom, until he realised that the scrutator was watching him. Flushing, Nish looked away.

‘Go on,’ said Flydd to Ullii.

‘Tiaan was terrified. She made the hedron spit fire.’

‘Fire?’ cried the scrutator.

‘Fire like a purple fan. The crystal became so bright that it hurt my head. I could not see the lattice at all. The fire burned holes in the wall and I lost her. I have not seen her since.’

‘What wall?’ said the scrutator urgently.

‘A tower that is a mountain, with water all round.’

‘What else do you know about that place, Ullii?’

‘That’s all. I only saw it once.’

Xervish lurched crabwise to the door, taking a map from his bag. ‘A tower that is a mountain, south-west of here.’ He traced her sighting line on the map. ‘Of course, Lake Kalissi! It has a great spire in the middle, of natural iron. A very strange place. There have been rumours of lyrinx there!’

He paced back and forth. ‘Then we won’t need the balloon,’ Nish said, disappointed that his idea would come to nothing after all.

‘Of course we’ll need the damned balloon! She may have escaped, since Ullii can no longer see her. If Kalissin is a base for their flesh-forming, we’ve got to find out what they’re making. Fire coming out of a hedron, strong enough to burn holes in a wall! If somehow Tiaan has uncovered real power, we’ve got to have it before the enemy does.’

There were many trials over the next few weeks, not all successful. Two balloons crashed and caught fire. Another burned in mid-air, raining blazing debris and bodies down on the miners’ village, including an unfortunate Porthis. Yet another balloon refused to take off at all; a leak was discovered. Two more, the third and the last, were moderately successful. The last rode up over the mountains, to be caught by the wind and driven for ten leagues in the direction of the plateau where the bloody battle with the lyrinx had occurred.

Ullii saw no more of Tiaan. She had vanished like an exploding star. Work on the final balloon continued. It was designed to lift ten people – Nish, Ullii and eight soldiers, to be led by Rustina – and all their gear. They were to capture Tiaan and bring her back on foot, since suitable winds for the return journey were unlikely. That was the problem with balloons.

The best part of two months had passed since the last sighting of Tiaan, and winter was almost over, by the time the balloon was assembled. It was made of tar-sealed silk stretched over a frame of light wood reinforced with tensioned wires. The structure was highly flammable but that could not be helped. Below the mouth sat a brazier built of wire mesh lined with furnace tiles. Below that hung a platform with basketweave sides, where they would eat, sleep and live. Fuel for the brazier would be stored there but they would have to replenish it on the way. They could not carry enough to take them to Kalissin, unless the winds proved particularly favourable.

The completed balloon, nearly fifteen spans high, not counting the basket, and ten wide, had used all the silk cloth in Tiksi. A valve at the top could be worked by a rope, to spill hot air and allow them to control where they landed.

The balloon’s bracings kept it semi-rigid, so it looked as if it was ready to take off even when there was no hot air in it. It had been tested with different fuels while artificers measured the pull on springs attached to the ground, to see how much lift each fuel gave. Wood could be used if they had nothing better, though it had to be dry and took up a lot of space for the heat it gave out. Pitch or furnace coke were better, but pitch produced noxious black fumes and coke also required much space. Best of all was a clear liquid distilled from tar heated in an airless furnace, though it was dangerous to handle and liable to explode at the slightest spark.

One evening Irisis went to the scrutator and begged to be allowed to go on the balloon. She could not stop thinking about Tiaan’s crystal.

‘What on earth for?’ His single brow wrinkled into a series of furrows. ‘What could you do that would justify the disruption your absence would cause here?’

Irisis had a carefully prepared rationale but before that cold stare it seemed childish. She dropped her gaze.

‘You do want to be crafter here?’ he said softly. ‘The breeding factory is only a suspended sentence, remember.’

Irisis felt that he was peering inside her head, and that he knew, and had always known, what a fraud she was. Under her, the artisans were producing more and better controllers than ever, but no doubt he enjoyed having that hold over her.

‘All I ever dreamed about was to be crafter.’

They still had a week’s work to do when Ullii found Tiaan again. She was practically due west this time. ‘Lakes and mountains,’ said the seeker.

‘As before?’ Nish asked.

‘No, big, big mountains.’

‘Sounds like she’s gone north from Kalissin,’ said the scrutator. ‘To the Great Mountains. She could be anywhere along a line a hundred leagues long. There’s nothing for it, artificer. You’ll have to leave at once.’

‘The balloon isn’t finished.’

‘It will be. We’ll work night and day to make sure of it. You’ll go at dawn the day after tomorrow.’

Nish marked Ullii’s direction on the map he was to take with him. On the last night the seeing was so strong that Ullii grew agitated. ‘Fire and smoke, Nish!’

‘A campfire?’ Nish asked.

‘Big fires. Fires coming out of the tops of mountains.’

The scrutator was alarmed. ‘I don’t understand. She’s seeing volcanoes? There are no volcanoes in that land, or anywhere between the Great Mountains and the inland seas. Can her directions be completely wrong?’ He cracked his crab-limb finger joints in agitation.

Further questioning revealed that the volcanoes were visions of Tiaan’s, not what Ullii was actually seeing. The scrutator was not comforted.

‘I don’t like it. I wonder if I should come too?’

Nish did not care for that idea. There would be no credit in it for him if the scrutator led the expedition. ‘Maybe better that I take a skeet to send word back,’ he said carefully, ‘and you remain here where you can act swiftly, should the need arise.’

Flydd gave him a knowing glance. ‘There are arguments either way. I’ll make my decision in the morning. Meantime, if I am to go, there’s much I must record first. I also answer to unforgiving masters, artificer.’

Nish took the hint.

Dawn came and went. The wind blew in the right direction but the balloon was not ready, though everyone had worked through the night. Nish was utterly exhausted as he humped his pack out the front gate. He sat on it while the last checks were done.

Irisis was pacing round and round the basket. She wore full mountain gear, including down-filled jacket and pants. Was she planning to jump on at the last minute? Nish hoped not.

The scrutator was also dressed for the cold, though he was calm. ‘Have you decided, surr?’ Nish tried to conceal his nervousness.

‘I believe I will come with you after all. There is much to be learned about this new means of transport.’

Nish’s heart sank to his knees. ‘That is wonderful, surr,’ he lied.

The scrutator frowned. ‘It’s not a reward, artificer. This is a desperate venture. The chance of any of us getting there is slim. The hope of us coming back alive, with her, almost non-existent. You do realise this?’

Nish had been trying not to think about that but of course Flydd was right. This was not a bold mission but a suicidal one. What would they find at the destination? Most probably a lyrinx dining table.

‘You can still back out,’ the scrutator said quietly.

‘And confirm your opinion of me, and my father’s?’

‘You don’t know what my opinion of you is.’

Nish thought for a minute. He did not have to go, and all his life he’d taken as few risks as possible, never losing sight of his goal. He could stay behind, work hard at his craft and probably rise in it. The war offered many opportunities. And there was Irisis too.