Forgre held a white dish to Bilfis's back, probing the bloody residue with a forefinger. 'I think you may have got it,' he said.

Bilfis looked down at the dish and gave a rueful smile. 'I never thought-' He stiffened, gave the faintest of sighs and, with no other sign, he died.

'I wasn't quick enough.' Malien covered her face with her long fingers.

'No one ever is,' said Talis, closing the man's eyes.

Tiaan had expected them to take Bilfis's body to the Well of Echoes, but Malien was reluctant to do that given its unstable condition. They flew him up to the icefield on the high plateau, higher than Tiaan had ever been, where the cold was unrelenting. Malien melted a hole with the underside of the construct and slid the body in. Within a minute the water had frozen again, leaving him encased in ice as clear as glass. The Aachim sang a threnody in an archaic tongue.

'He loved the mountains,' said Malien, panting in the thin air. 'Bilfis would be happy that we've brought him here, where no other Aachim foot has ever trod.'

'No foot of any kind, I think,' said Talis the Mapmaker. 'No one could survive in such a high place.'

'Including us!' said Malien. A hundred thousand years from now he'll lie here unchanged. That would please him very much.' She headed for the thapter. 'But what are we going to do without him?'

They continued on to Snizort, flying long hours every day. It still took four days. Tiaan made measurements of the nodes whenever she got the chance, and marked them on the maps. Incessant work helped to keep her thoughts at bay. They passed by the battlefield, towards the Sea of Thurkad, and thence up the coast. The following afternoon they came upon a large encampment in a long but narrow inlet which had rocky ridges on either side. The camp was surrounded by a palisade of sharpened timber, the new home of exiled Clan Elienor. Tiaan saw no more of it, for as they approached Malien said, 'Go below.'

Tiaan searched Malien's lined face. Am I in danger here?'

'I don't know. It depends whether an outcast clan considers themselves bound by clan-vengeance. I won't risk it. Stay hidden while we unload the food and other supplies, and then we'll see.'

Tiaan spent the afternoon huddled under a blanket, trying to shut out the world. She could not erase her thoughts. The following morning Malien woke her. Talis and Forgre were there too.

'Stay where you are until we're in the air,' said Malien.

Where are we going now?'

'West.'

Across the sea to Meldorin?' said Tiaan. 'Where the lyrinx are?'

'We came at an opportune time. My people have just had vital news.'

'Oh?' said Tiaan.

'With Bilfis dead, only one person has the skills of geomancy and mathemancy to tell us how bad the node danger is, and how to avert it - the tetrarch, Gilhaelith. I now know where he's hiding.'

'Where is he?'

'He's north across the Sea of Thurkad, near a lyrinx city called Oellyll.'

Tiaan did not recognise the name, though it sent a shiver up her spine nonetheless. 'Is he a prisoner?'

'I don't think so. Word has it that he's made a deal with the enemy.'

Fifty-four.

'What's the name of this place?' Tiaan asked as they were crossing the Sea of Thurkad.

Malien was at the controller. The sea here, almost eighty leagues north of the place where she had escaped from the Aachim nets, was more than twenty leagues across. In the distance she saw a gap in the range that ran down the east coast of Meldorin. The peaks were white, the flanks of the mountains dusted with an early fall of snow, for it was late autumn now. To the left, a steep-sided volcano fumed. There was no snow on its warm flanks, though similar dormant peaks to its north and south had caps of white.

Malien did not reply. She was frowning at the sullen water far below. 'Better go up; we could be seen at this height.' She lifted the thapter into the bumpy air inside the clouds.

'That's the Zarqa Gap,' said Talis, pointing, 'one of the few passes across these mountains, at least in the wintertime. See the ancient road?'

The thapter lurched. Tiaan caught another brief glimpse of the pass, then they were in opaque cloud again. Talis was silent until a second filmy gap appeared. 'It used to run all the way to the west coast, though already the forest is taking it back. The lyrinx eliminated the last people from these lands a generation ago.'

'Down south,' said Malien, 'further to our left, lie the ruins of Alcifer.'

There was nothing to see but cloud. 'I've heard that name,' said Tiaan. It gave her a shivery feeling.

'The city was designed by the brilliant architect Pitlis, for Rulke, and Rulke's seduction of him is the greatest betrayal in the Histories. Many people say that Alcifer was the greatest creation of any of the human species, anywhere in the Three worlds. It caused the downfall of my people, from which we have never recovered.'

The clouds broke and Tiaan pointed a spyglass where Malien had indicated. The mountains ran close to the sea there, and a flank of the volcano had been carved and sculpted to form the platform upon which Alcifer had been built. Great boulevards curved through it, and buildings great and small, their outlines just visible beneath aeons of growth, erosion and volcanic ash. From this distance no more detail could be seen.

On the slopes north of the city, the volcano had, long ago, formed a series of terraces covered in glittering crystalline salts, mud pools, geysers, fumaroles and the snaking lines of ancient lava tunnels whose tops had collapsed. Steam hung in wisps over the surface.

'That's chancy country,' said Talis, consulting an ancient gazetteer of the lands around Alcifer. 'When it rains, flows of mud and ash are dammed up against the edge of the terraces. They crust over in the dry season, though if you tried to walk there you'd go straight through.'

And slowly cook in hot mud,' said Forgre. 'Not how I'd choose to die.'

'In really wet years,' said Talis, reading from the gazetteer, 'the terrace walls burst and the hot slurry pours down the slope faster than a horse can gallop, sweeping trees and boulders away.'

'Chancy country indeed,' said Malien, rising into the clouds again.

'Is Alcifer in the Histories?' Tiaan asked.

'It's in the Tale of Tar Gaarn, which is in our Histories, but it's not much told these days. Rulke scarcely had the time to enjoy his creation, for soon after Alcifer was completed he was taken by the Council of Santhenar and cast into the Nightland; where he languished for a thousand years. Once freed, as far as is known, he never returned to Alcifer and it was never inhabited again. Who would dare?'

Have you been there?'

Malien shivered. 'No, and I'm not looking forward to it. I feel the threat, even from here.'

Tiaan opened her mouth but closed it again. Malien was the most level-headed person she know. 'Where are we going now?'

'We'll fly across the range, then swing back and come on the place at night, on foot.'

The idea seemed absurd. How could they hope to find Gilhaelith in such a vast city, with so many lyrinx below and nearby? And if they did, how could they hope to free him?

They crossed the range north of the Zarqa Gap, at a pass that bore just a dusting of untracked snow. Keeping to what cloud they could find, they continued west over grassland and forest. The sun was sinking over the impassable swamp forests of Orist as they made a sweeping curve south and then east, approaching the range at its widest point, well south of Zarqa. Malien worked a set of concealed controls beneath the binnacle, then took the machine down as the sun set, cruising in the light of the stars, just above the treetops. It was eerie; everything was black and white and Tiaan found it difficult to measure distance. Trees and rocky peaks rushed at them out of nowhere.

'Aren't you worried about being spotted?' said Tiaan.

'I've just put a concealment on the thapter,' Malien said cryptically. 'It's quite effective from this distance, though I don't know how long I can keep it up.'

They floated above the treetops for hours, Talis and Forgre staring at their maps and conversing in whispers, before Talis said, 'Go down onto that bare spur, just to the left.'

Malien settled the thapter expertly on a shelf of some pale-coloured stone, shaped like the bowl of a spoon. A tree with a split trunk, black against the white bark, leaned out to overhang the end of the ridge.

'This is as close as we dare go,' said Forgre, rubbing his i beardless cheek. 'We're but two leagues from Alcifer and Oellyll, the lyrinx city beneath it. Tens of thousands of lyrinx dwell there, and they hunt in these mountains.'

Are we close to those terraces we saw yesterday?' said Tiaan. She could smell brimstone.

'They're that way,' said Talis, pointing towards the sea. They run east for leagues, then north high above the coast.'

'If you listen closely,' said Malien, 'you can hear the geysers going.'

No one spoke for a while, and in the distance Tiaan heard a rushing sound that built up to a muted roar before fading away.

'It seems a little risky, going down to Alcifer on foot,' she ventured.

'You mean insane and incomprehensible,' Malien observed dryly. 'I daren't take the thapter any closer. No concealment is perfect.'

'How are you going to find Gilhaelith in such a vast place?'

'We have certain information about his whereabouts.'

'How can you be sure it's reliable?'

'That's Forgre's job,' said Malien. 'He's our most gifted spy. Apparently the lyrinx shun Alcifer itself, so if Gilhaelith is there, using power, he won't be hard to find. Once Forgre discovers where he is, we'll fly down and snatch him.'

'Just like that?' said Tiaan.

'I hope so.'

'If Gilhaelith's in Alcifer, he must be trusted by the enemy.'

'He may be assisting them,' Forgre said, 'but I doubt they trust him.'

'From what I hear of Gilhaelith, he's always out for himself' said Malien. 'I'd say they have some hold over him.'

Tiaan walked to the edge of the rock and stood looking down. The deep valley was like a pool of ink with a few pinpoints of light floating on it, starlight touching the tips of the tallest trees. She was so afraid, her knees would barely hold her up. Tiaan had sworn, after her captivity in Kalissin, that she would never go near the lyrinx again. But she had, and they'd put her into the patterners in Snizort. It was a horror she thought about every day.

Malien moved the thapter into deeper shelter and strengthened the concealment. 'That should be enough. It's a balance between doing enough to conceal the machine but not so much as to alert the enemy.'

'What if a lyrinx chances to walk past?'

'Any ordinary lyrinx could walk right into the thapter and just think it was rock. It hurts me to maintain it, though, so I hope it's not necessary for long.'

Malien turned into the forest. They followed silently, after an hour coming onto a narrow ridge that terminated in a cliff.

Malien peered over with her spyglass. 'Alcifer, look!' The hairs stood up on her nape.

Domes and spires rose out of woolly fog that hung in the hollows of the abandoned city like a bathtub full of kapok. How could a place abandoned so long ago still seem to hold such menace?

Forgre had been out several times. Tiaan had wondered how he could pass through the lyrinx guards into Alcifer, until she saw him in action. A master of the spying Art, he could blend into the background as well as any lyrinx, and when he moved it baffled the eye. It took a lot out of him, though; Forgre was always exhausted when he came back.

On their third day of watching, an air-floater appeared through a gap in the clouds and circled above Alcifer several times, before disappearing into the clouds again.

'What's that doing here?' hissed Malien.

'Oellyll is the greatest enemy city,' said Forgre. 'The scrutators often spy on it, now that they can fly above lyrinx height.'

'I can't imagine they'd see much from such an altitude.'

'It must be good for old-human morale.'

'Unfortunately for us, it'll make the lyrinx more watchful than ever,' said Malien.

'It may draw them away from us, at least.'

Their fliers will be looking down as well as up.'

Then we'll just have to be even more careful,' Forgre said arily.

'Ah, I'm done in,' he said on his return from another mission. It was around midday on their fifth day of watching, and they were still camped by the lookout. The weather was cold and gloomy, with driven rain-showers, a chilly wind and occa-signal breaks of a watery sun that silvered the metal domes of Alcifer, far below.

Tiaan took up the spyglass and, as she had done a hundred times in the past days, swept it around and over the city. When the scudding showers passed, she could see slaves toiling in the lower gardens.

'Did you find him?' said Malien.

'No, though I know he's there.' Forgre looked down at his wiry hands, which were shaking. 'I'll have to rest awhile - my aftersickness is bad here.'

Tiaan looked through the spyglass again. 'He's there.' 'Forgre just said that,' Malien reminded her. There! Look!' Tiaan rose to her feet, pointing to a ridge east of theirs, which was rather lower. Its point, bare of trees, was momentarily exposed through the drifting mist.

Malien snatched the glass. 'I see six slaves, no, eight. They appear to be making readings of the field, at the direction of a very tall man. There could be more slaves in the shade of the trees.'

'It's Gilhaelith!' Tiaan whispered. 'Are you sure?' 'Positive.'

'How long have they been there?' 'I don't know. The mist has only just cleared.' 'They'll probably be taking readings for a while,' said Malien. 'This is the best chance we'll ever get. But how to do it?'

'Why not just fly there and grab him?' said Tiaan.

'The guards will hear the thapter long before we get there.

I can't conceal that. Once they do, the illusion will break and they'll vanish into the forest with him. We'll have to get to Gilhaelith on foot. Tiaan, slip back to the thapter and take it across, but hang further up the ridge, in the mist. My concealment will hold as long as you don't get too close.'

'What are you going to do?'

'We'll go across, also under concealment, and hide near the wall of the lowest terrace. I'll know when you're coming and take Gilhaelith. The instant I signal, race down and pick us up.'

'Are you sure you can do it?'