A catapult ball sang overhead, smashing into one of the furnace chimneys, which collapsed in a shower of bricks. The masons and bricklayers would slave for a fortnight to repair it.

Crouching between the battlements, Irisis sighted on a large, green-crested lyrinx that seemed to be directing the attack from the eaves of the forest. Stay where you are, just another second. She fired. The lyrinx jerked, then slapped a hand to its breast. The bolt had gone low, embedding itself in the breast plate. The creature would be sorely bruised but no real damage had been done. It raised its fists to the sky in a voiceless cry.

Irisis was reloading the clumsy weapon when someone cried, 'Look out!' and she was struck hard between the shoulders. The crossbow skidded down the paving, struck the wall and went off, firing its bolt into the stone.

Irisis was on her knees, trying to work out what had hit her, when she was lifted in the air. A hovering lyrinx had her in its claws, flapping desperately. She must have weighed more than it had antic.i.p.ated.

She thrashed her arms and legs. Her coat tore and she fell free but the creature slashed out and its claws went through her collar. The beast wobbled in the air as it tried for a better grip. She kicked, caught it in the groin and it went close to dropping her. Its eyes were staring, its breath coming in tortured gasps.

Irisis tried to pull out of her coat but could not get her arms free. She smacked at the face of the lyrinx, which snapped back, almost taking her hand off. Its wings beat irregularly as it struggled to gain height. She attacked again and managed to poke it in the eye with a finger. It canted sideways, its eye closed and she thought it was going to fall over the edge.

Its head lunged, the great teeth snapping so close that she smelt its hot breath. The abduction had failed; now it was trying to kill her. Irisis drew her legs up and kicked it in the jaw. The lyrinx howled and almost fell out of the air. She was a heavy burden for a creature that required the Secret Art to keep its own weight aloft. Irisis touched the artisan's pliance hanging around her neck and could sense the distortion the lyrinx was making in the field.

She kicked again but it held its head well back now. Its free hand went for her throat, but so slowly she had time to get her arm across. The claws tore harmlessly through the heavy fabric of her coat. The lyrinx gained control, the great wings beat and it lifted. Irisis could see the guards, their weapons tracking the creature, but no one dared shoot for fear of hitting her.

The scrutator came running up the steps, only to stop at the top as if he had run into a wall. The beast was gaining height now, drifting out toward the edge, its wings thumping the air. Just a couple of spans and it could let her go. She heard its rumbling purr. Irisis struggled but its grip was too tight. She had no knife or any other kind of weapon. She kicked and missed. Kicked again.

The creature rotated in the air. Time seemed to be going so slowly. Flydd was up on the edge of the wall, then he whirled, racing for the steps that led to the lookout above the gate. What was he doing?

Appearing at the top of the watch-tower, he took a flying leap out across the angle of the wall. She felt sure he was going to fall to his death, but the lyrinx drifted underneath and he landed with a thump that drove it out of the air. Irisis crashed into the battlement, the creature landing on top of her with stunning impact. It slid down onto the walkway, its skin flaring bright orange, claws sc.r.a.ping the stone beside her face. Lowering its head, it thrust forward. Her arms were trapped. All she could do was draw her knees up before her face. The lyrinx wrenched them apart and kept coming.

The scrutator's knife dug in between the neck plates and dragged across. Hot blood exploded from its throat, spraying the stone, her face and her hair. The lyrinx stopped struggling. Two soldiers dragged her out from underneath and she watched the great beast die, its eyes slowly closing, the head drooping. The death colours mottled yellows, greens and scarlets kept on flickering long after life was extinguished.

Irisis could not stand up. Flydd wiped the blood off her face, sat her with her back to a battlement and put her crossbow in her hands.

'I told you to be careful. Get your breath. We've a long way to go.' He ran down the wall.

A ball smashed stone into stinging gravel. Another crashed through the light-tower, scattering blazing tar-soaked straw everywhere. Little fires began on the roofs. Attendants scrambled to put them out.

A boulder struck the ma.s.sive iron gates below their section of the wall, tearing one off its hinges. Another ball hurtled through the gap, followed by a third, equally large. A splintering crash was confirmed by the doorman's shout.

'To the gate! The inner gate is broken.'

Levering herself to her feet, Irisis peered over. The lyrinx charged in a group. In the gloom she could not count their numbers. One fell outside the iron gates, another on the step, struck down by a lump of rock dropped from the wall, but it got up again. She fired her crossbow as fast as she could load it, though soon there were no targets left. The survivors were inside the manufactory.

The attacks on the wall continued, the catapults firing from the edge of the forest. In the dark it was almost impossible to hit them, while the soldiers on the wall were easy targets. A splatting thud signalled the end of another guard.

Not long before dawn she saw Flydd hauling himself up the stair by the railing. He looked as if all the blood had been sucked out of him.

'What's happening?' Irisis yelled.

'They drove us right through the manufactory, but we ambushed them near the furnaces, firing red-hot bolts. They didn't like that at all. We killed five and injured the others, and they fled out the back door.'

'Red-hot bolts,' said Irisis. 'Whose idea was that?'

'One of the artificers. He's dead, now. It turned the battle though; changed minor wounds into disabling ones.'

Irisis, imagining the agony of such a wound, felt ill.

'We've suffered terrible casualties,' he went on. 'At least sixty dead and as many wounded. We can't take much more, Irisis.'

'They're only firing intermittently now. I'd say they've had enough.'

'There were sixteen and we've killed eleven, at least, but don't think this is the end of it. They'll be back.'

'They're deadly accurate with those catapults,' said Irisis. 'Do you think the attack on me was deliberate?'

The scrutator was aiming through an arrow slit with a borrowed crossbow. He fired. 'I do. They've kidnapped artisans before. It went straight for you and would not let go even when that risked its own life. They don't usually go for suicide missions so they must have wanted you badly.'

'Or wanted me dead. Thank you, Xervish.'

'We also want you badly,' he said dismissively.

Shortly afterwards the attack ended, the surviving lyrinx fading into the forest. By daybreak there was no sign of them. Flydd called a meeting in the refectory to review the damage.

'The gates and front doors will have to be completely rebuilt,' said the chief mason. 'We'll make a temporary wall out front, not that it'll do much good. If they attack tonight with as much force, I don't see how we can survive.'

'I'm sure they will attack tonight,' said Flydd. 'They'd be fools not to.'

There was worse news and it was not long in coming. Chief Miner Cloor, a little nuggetty fellow whose pores were so impregnated by mine dust that it looked as if he was covered in blackheads, stumped in.

'The lyrinx have taken the mine, surr.'

'How many?' asked Flydd. He did not look surprised, though his scrawny shoulders drooped even further.

Irisis felt for him. Since he'd arrived there had been one disaster after another. He would be blamed for them all.

'Can't tell, surr. We saw five or six behind the grid. That could be all ...'

'Or there could be another hundred down there,' said the scrutator bleakly. 'Evacuate the miners' village, chief miner. We can't defend it as well.'

Cloor nodded and stumped out again.

After the night's exertions, few people were able to work. In the case of Irisis's artisans, it hardly mattered, since they already had a large store of controllers a.s.sembled, awaiting hedrons to complete them. That was looking increasingly unlikely now.

Irisis s.n.a.t.c.hed a few hours sleep then returned to the refectory, where she found the scrutator sitting at a table in the far corner with the chief miner, Overseer Tuniz and Captain Gir-Dan. Maps of the various levels of the mine were spread out in front of them.

'They must have come in through the lower tunnels,' said the captain. 'The enemy had captured the mine before the outside guards knew a thing.'

'Unless they had skived off from their duty,' the scrutator said darkly.

'Let's have no talk of neglect of duty, if you please, surr,' said Cloor. He was as irascible as Flydd, with little respect for any authority save his own.

Flydd gave him a black stare. The chief miner glared back. Neither broke. 'Enough,' Flydd said finally. 'The fault does not matter. What can we do about it?'

'I've talked with my surveyors. We're sure they're getting in this way.' Cloor's battered fingernail indicated a long tunnel down on the ninth level. 'If we could drop the roof here, we'd have them trapped and it would just be a matter of winkling them out.'

'Deadly winkling,' said the captain. 'A dozen lyrinx would be a match for fifty of my men, down there in the dark.'

'I'd starve them out,' snapped Cloor. 'Not even lyrinx can go a month without food.'

'I can't wait a month for crystal. How long would it take to bring down the roof?' asked the scrutator.

'We could do it in a few hours in this section.' Cloor's finger marked an 'X' on the map. 'And it's relatively close to the workings. Of course, we'd need a strong guard.'

'At least forty men,' said the captain.

'If I send that many down,' the scrutator mused, 'and they attack here, as they are bound to do ... We might well lose the manufactory.'

'Without the mine there's not much point to the manufactory,' said Irisis.

The scrutator dismissed that with an irritable sweep of the hand. 'The mine is just a hole in the ground, but to replace this manufactory would take five thousand people working for four years.'

'What do you want us to do?'

'Get some rest. We'll be on the wall again tonight, I'll be bound.' Flydd rose. 'What do they want?' he muttered on the way out. 'Do they aim to deny us the crystal, or is there something more sinister at work?'

That night, on the gong of midnight, the lyrinx attacked again. Irisis had just dozed off when a catapult ball, fired up at a steep angle, came smashing through the roof a few doors away, demolishing the room of one of the recently arrived artisans. The silence was followed by her screams, then shouts as the manufactory scrambled out of bed.

Irisis was the first to get there. The artisan lay in the splinters of her bed, unharmed but screaming her lungs out. More b.a.l.l.s began to fall, so swiftly that the catapults must have been firing many at a time. Though only the size of melons, they wrought terrible damage. Not all the sleepers were as lucky as the first.

Irisis dressed and put on the metal hat she wore down the mine. It would not save her from these missiles, but might protect her from the slates that were falling all around.

There was a lull of a minute or so. She ran into the scrutator in the corridor. 'What are we to do?' she shouted.

'It's not this I'm so worried about,' he said, 'though it's doing damage enough.'

She looked up through one of the holes in the roof. 'What are are you worried about?' you worried about?'

'Fire ' As he spoke, a flaming ball descended from the sky, hit the roof and slid in through a hole to land in one of the ruined rooms. Flames leapt up. Irisis grabbed a fire bucket and emptied the sand on it.

'What is it?' the scrutator yelled.

'Rock dipped in tar.'

Soon blazing missiles were falling all around. Irisis and fifty other people were kept busy putting out the fires. They still had many to go, and the fire team were attaching their canvas hoses to the hand pumps when the barrage stopped. At once the attack on the walls and front gate resumed.

'I don't think we're going to survive this time,' said the scrutator as their paths crossed again. 'Better pack up your gear.'

She stopped, staring at him. 'What do you mean?'

'We're leaving leaving.'

'How?'

'I try to plan for all contingencies. The air-floater is standing by, up in the mountains. I've signalled it to come.'

'It'll be a sitting target, floating over the manufactory.'

'It will drop down behind the ridge. We'll sneak up inside the aqueduct where the enemy can't see us.'

'The air-floater won't carry a thousand people.'

'Not even twenty. The rest must stay behind.'

'To die!'

'More likely they'll be left alone once we're gone.'

'I've worked with these people for most of my life,' she said. 'I'm not leaving them.'

'I'm ordering you to. Anyway, we'll be in more danger than they are.'

Alhough Irisis was quite selfish, she could not bear the thought of running away. 'I've got work to do!' she snapped and went back up. The fires were under control now and Irisis preferred the danger of the wall; at least she could see what was coming.

They were losing. The lyrinx had an uncanny sense of where to aim and their catapults picked off the guards one by one. Half were dead now, and most of the survivors carried injuries. Their replacements were just ordinary workers who did little damage to the enemy and were slain in droves. The dead still lay where they had fallen hours ago, for no one could be spared to carry them away. Irisis had known them all for years.

She checked the sky. Dawn was not far away but there was no sign of the air-floater and the scrutator had sent no message. Finally she dragged her exhausted body down for a drink and a bite to eat, a few minutes' relief from the h.e.l.l that was the wall.

The scrutator was in his room, writing furiously. 'What's happened to your air-floater?' she said sarcastically. 'Another failure?'

Irisis regretted this the moment the words left her lips, but Flydd did not react. He looked numb.

'There's been nothing since I signalled. The lyrinx must have caught them.'

'Then we're finished,' she said.

'It seems so. I'm sorry.'

'Oh, well. I've been here before. And survived too.'

'I doubt you will this time,' he muttered.

'It was borrowed time anyway.'

There was a great roar outside. 'See what that is, will you?' he said, without looking up.

Irisis ran to the front gate, where she encountered Tuniz. The overseer had blood all down her front, though it was not her own. 'How are we doing?' Irisis gasped.

'We beat them back but I don't think we can do it again.'

Irisis peered through the broken gate. 'It's not long until dawn.'

'That won't stop them this time. They're too close to victory.'

Irisis ran back to report. 'The gate still holds,' she said to the scrutator, 'though it can't last long.'

'We'll be overrun by sunrise.' He carried a stack of papers to the furnace and heaved them in. They burst into flame and were sucked up the chimney.