She did not respond. He shouted the same words again, jerking on the lines as hard as he dared. No answer. The top of the peak came up, too quickly. They were drifting right at the spires.

‘Besant!’ he screamed, so loudly that it hurt Tiaan’s ears. ‘Wake or we are ended and the war is lost.’

Besant gave a faint convulsion. One leg kicked. She raised her head and her left wing extended, clawing them round the main peak straight toward a smaller spire of iron.

Ryll flung his weight sideways. The wing flier banked, shot past the spire, just skimmed another; and then Besant’s wings flapped twice, lifting her weight. They soared up and over, slowing rapidly. They were going to make it.

But Besant was finished. One wing tore, she struck the edge of a third spire and fell thumping all the way down. The wing flier turned upside down and broke in two. They plummeted a couple of spans to the ground, Ryll landing on his back with Tiaan on top of him.

She lay there, stunned and aching all over. Three lyrinx came bounding up. Slashing her free, they hauled her off Ryll, who was unconscious. The largest lyrinx spoke to Tiaan in a language she did not know. Another ran to the crumpled figure of Besant.

‘I do not understand you,’ Tiaan said carefully, using the common speech of the south-east.

Ryll sat up, shaking his head. A horrible groan rent the air. It was Besant. The lyrinx turned to her. She tried to roll over but purple blood ran out of her mouth. As they attempted to lift her she gave a wracking cry.

One lyrinx began stripping the broken flier down to its wooden members. Another carried several struts and a piece of fabric across and lashed them into the shape of a stretcher. A third wiped blood from Besant’s mouth, gibbering at her in that strange tongue. Her hand pointed to a small pack bound between her breast plates. Someone unfastened it, drawing out a leather case. The lashings were untied. A female gasped, her crest went a luminous green and she held the amplimet high. It glowed much more brightly than usual. Light was positively flooding from it.

Besant choked out a few sentences, in one of which Tiaan heard her name, somewhat mangled, ‘Tee-yarrrn.’ The lyrinx swung around, all staring at her. Besant continued, her voice rising.

‘Myllixyn thrruppa harrh, ghos tirri Ryll!’ She screamed out the last three words, flung an accusing arm at him and slumped sideways, coughing purple bubbles.

The lyrinx who had cut Tiaan’s ropes covered the ground to Ryll in three great bounds, hauled him to his feet and struck him hard on the forehead, three times. Ryll bowed his head and held out his hands. The lyrinx bound him swiftly, Ryll showing no emotion, nor any reaction to the pain as his injured arm was jerked about. He was led away.

Another collected his pack, and Tiaan’s, and pointed toward the sinkhole. She moved that way. The remaining lyrinx had eased Besant onto the stretcher and were rigging ropes on a tripod above the hole. Tiaan was led down a narrow iron ladder whose rungs were uncomfortably far apart.

The first thing she noticed was the noise, or rather, music, a low droning that went up and down like someone blowing through long tubes. It was in the background all the time. Sometimes the sound went so low that she could feel it in her bones.

As she stumbled into the dark, Tiaan wondered if she would ever see the outside again. It was the strangest place she had ever been. The inside was like a frozen foam of grey, rust-streaked iron, every surface being curved like the interior of a bubble. A long way below, past various guard chambers and working spaces whose purpose she could not discern, she entered a large circular chamber shaped like two saucers, one right way up with another upside down on top of it.

She was taken down a sloping floor to the depressed central section. To one side stood a round table, a pitcher and a set of mugs the size of small buckets, all made of iron. Ryll was led in, followed by Besant on her stretcher, her breast plates streaked with coughed-up blood. The stretcher-bearers set Besant down on the rim. Some dozens of lyrinx took up positions around her.

A young female, whose skin plates were so soft and unpigmented that Tiaan could see her breasts through them, gently held up Besant’s head. A huge female bent over her, in the attitude Ryll had adopted when regenerating his hand. She stood up, shaking her head.

‘Would you speak, Wise Mother?’ she said.

Besant mumbled in her incomprehensible language. Every word brought bubbles foaming out of her mouth and nose. Again she spoke Tiaan’s name and everyone stared at her. A massively built male, with green eyes shaded by brow ridges like shelves, produced the amplimet. It lit up the room with streamers of radiant light.

He gestured to Tiaan. The big female, who had yellow skin plates and sagging wattles at neck and chin, spoke Tiaan’s language in a crackling voice. ‘I am Coeland, Wise Mother of Kalissin. Show us the devices, human.’

Not daring to disobey, Tiaan donned the helm, held the wire globe in her hands and waited. Everyone was watching her.

‘The amplimet goes inside,’ Tiaan said.

Coeland gestured; the male with the brow ridges brought the crystal across. Before he reached her Tiaan felt the potential of it, stronger than before. There had to be a powerful node here.

Her craving for the amplimet was unbearable. Tiaan’s eyes watered. She opened the globe so he could place the crystal inside. The light flared. He cried out and dropped the crystal. She caught it in her hands, a moment of painful bliss, then slipped it into the globe, closed it and fastened the catch. The lyrinx sprang out of the way as if it had bitten him.

Tiaan put down the globe. The field was so bright here that she could visualise it with her eyes open. The node must be a monster. She moved the helm on her head, afraid of the amplimet now. It was definitely channelling power by itself, much more than before. It had nearly killed her in the ice sphere, and there it had been much dimmer.

‘Show!’ Coeland said imperatively.

Tiaan adjusted her helm, reached for the globe, shrieked and snatched her fingers away. The wires were too hot to touch. Suddenly the metal table, pitcher and mugs were pulled up to the ceiling, where they stuck as if magnetised. Water rained down, sizzling on the wires. Her hair began to smoke. Ryll lurched forward and knocked the helm off with his bound hands. The light died down. He caught the falling table and pitcher, though the mugs clanged on the floor.

‘You see,’ he said to the Wise Mother. ‘It taps great power but it is a dangerous device to control. She does not know what she is doing.’

‘The field is strong here,’ Tiaan said shakily, inspecting her fingers, which had lines burned across them. What if they thought it too dangerous and disposed of her? ‘It takes time for me to learn a new field before I can control the flux of power.’

‘We’ll see about that,’ said the elderly lyrinx. ‘Tell us about the tetrarch, human.’

Again that question. ‘I don’t know what a tetrarch is,’ Tiaan said

Again that interrogative stare, as if the lyrinx was trying to read her for the truth.

‘It is a person we would very much like to find.’ She turned to Ryll. ‘Besant accuses you of cowardice, wingless one! You were to remain behind. How do you defend yourself?’

Ryll shook his head. He sat holding his shoulder, which was inflamed around the crossbow wound. ‘No defence.’

‘Then Wyrkoe will be your defender.’ At her gesture a tall, slender female stood up.

‘No!’ said Ryll. ‘No defence.’

Wyrkoe sat again.

‘In that case you must take the consequences. You will be neutered at first light.’

Tiaan was shocked. What was the matter with Ryll? Was he too proud to defend himself, or had he given up? She looked around at the hard faces. After all he had done for her on the journey she could not see him treated so unjustly. Dare she?