Irisis wished Ullii were here now. Objects powered by the Secret Art appeared in the little seeker's mental lattice, which was how they'd located the node-drainer. Ullii could also see people with a talent for the Art, and most lyrinx. If she were here now, they would be able to avoid any enemy who remained inside, and quickly find the flesh-formed creatures that were their target. But Ullii had disappeared.

'Go down into that pit, Pilot Inouye,' said Fyn-Mah, pointing towards the largest, which contained only a haze of smoke. 'Soldiers, ready your weapons.'

Inouye's green eyes widened, but she nodded stiffly. The air-floater drifted towards the pit, just a spear-cast above the ground. The soldiers pointed their crossbows over the side while Irisis scanned the black, lifeless terrain. Nothing moved; with luck, all the lyrinx were gone.

They floated over the pit, a conical excavation in tar-saturated sandstone, with a ledge path spiralling down. Inouye vented floater gas. The air-floater lurched, steadied and began to descend through a rising trail of smoke.

'Where do we go from here?' asked Fyn-Mah, at her elbow.

Irisis did not answer at once. The black rock was featureless and it was taking her eyes some time to adjust. Tunnels began to appear, extending off the path. There were a dozen, at least, and smoke oozed from several. How could she possibly tell? It had been dark when she had come down previously, the night before last.

'We went down 741 steps,' she said, counting them aloud. Fyn-Mah did the same and checked her instrument again. 'There!' She pointed to a runnel near the base of the pit. 'Take us to that point, Pilot.'

The whirring of the rotor died to a gentle tick as they descended into the black pit. The reek, hanging heavier than air at the bottom, stung their eyes. They came alongside the tunnel and the soldiers tossed out grappling hooks, pulling the air-floater up against the steps.

'We're going in,' Fyn-Mah said to the captain. 'Bring five of your men. Scrutator Flydd has ordered me to recover certain . . , items from inside. The remaining four soldiers will guard the air-floater.'

The captain shuffled his feet. He looked about fifteen years old and Irisis felt sorry for him. 'I have orders to remain at my post.'

'Those orders are superseded.' She stared him down. 'This mission is for the good of the war, soldier, and we can't do it alone.'

He regarded his boots, glanced up at her, then nodded. 'So you won't mind giving your orders in writing.'

Fyn-Mah took a small piece of paper from her chest pack, scribbled something on it and stamped it with her personal seal. The captain read the document and put it in his wallet.

'Wait here,' Fyn-Mah said to Pilot Inouye. 'If there's danger, go up out of range and keep watch.'

'What if you don't come back?'

'Wait until dawn. If we haven't returned by then, you are released back to your master.'

The underground had a different feeling from Irisis's previous visit. Then it had been a vibrant, working city, still occupied by the lyrinx. Now it was a black, reeking hell where the ceilings had collapsed into heaps of rubble, the floors into fuming sink-holes and dead lyrinx lay everywhere. Fumes wisped down the tunnels like black spectres: sudden winds blew hot and cold; and, always in the distance, was the seething, bubbling crackle of burning tar.

They struggled through into a less damaged area, where they sought for the flesh-formed creature pens for hours without success. Fyn-Mah called out each turn and intersection as they passed it, Irisis noting them down so they could find the way out again. The air here was relatively clean, apart from drifting wisps of fume. Some of the tunnels were still lit by lanterns fuelled with distilled tar spirit, giving the air an oily tang, but they were guttering now.

Fyn-Mah stopped where the tunnel split into four. Consulting directions on a scrap of paper, she scowled. 'We must've taken a wrong turn. Do you recognise this place, Irisis?'

Irisis shook her head. 'The tunnels all look the same.'

'You're not much use, are you?'

'Ullii was leading us the other night,' said Irisis. 'It was dark, as I told you.'

'I can find my way around in the dark,' said Flangers. 'You get used to that, up on the shooter's platform. What if I were to take a few soldiers and go that way?' He pointed to the right. 'You could check the other tunnels.'

Fyn-Mah frowned. 'I don't want to split up, but I suppose there's no alternative. Irisis, take Flangers and him,' she indicated a soldier so young that he had no trace of beard, 'and go that way. We'll follow this tunnel. If you don't find anything in half an hour, come back to this point.' She scratched a zigzag mark into the wall with her sword. 'Don't get lost.'

'Let's have a look through this door,' Irisis said to Flangers. They'd searched dozens of chambers but had found nothing.

He gestured over his shoulder to the young soldier, a pink cheeked, frightened lad called Ivar. Irisis pushed the door open. Inside, in a damp, mist-laden space, stood three rows of objects that resembled chest-high pumpkins connected by grey vinelike cords.

'What do you suppose they're for?' asked Flangers.

'Something to do with flesh-forming. I expect; said Irisis.

He swallowed. That dark Art was beyond the comprehension of the greatest hero.

Other rooms contained similar objects, all with a vaguely organic appearance, all equally inexplicable. They passed out into a round chamber with a series of five closed doors on the far side.

'What a warren!' Flangers wiped sweat from his brow.

He opened the door on the left and uttered a low whistle. The room held ten cages, well separated, and inside each was a creature unlike anything he had ever seen: all horns, spines, teeth and armour plating. Each was different, and all were dead, killed by blows to the skull.

Irisis clutched the bars of the first cage, staring at the flesh-formed monstrosity inside. The grey-green, coated teeth were like shards of glass. 'Imagine that beast sticking its teeth into your leg while you're trying to fight the enemy.'

'It could bite straight through bone,' said Flangers. 'And it looks fast. It'd be hard to attack, too.'

'Doubtless they're breeding thousands of them. Ivar/ Irisis said to the young soldier, whose eyes were sticking out like boiled eggs, 'run and tell the perquisitor we've found them. Can you find your way back to the place where we separated?'

'Yes, Crafter.' Ivar ran off, glad to be going.

Irisis continued around the room. She was examining a beast whose maw was half the length of its body when Flangers called out, 'Irisis! This one's still alive.'

The creature, a heavy-headed monster with as many teeth as a crocodile and a row of yellow-tipped spines all the way down its backbone, lay on its side, its head half-covered in blood. The mouth was open and a trickle of grey matter oozed from one rimmed nostril. The chest did not move. As Irisis approached, the yellow and black eye shifted slightly, then the warty lid came down over it.

'It's dead now. We'll leave Fyn-Mah to check them,' said Irisis. 'Let's try the next room.'

It proved much the same as the first, and all the flesh-formed creatures were dead. Irisis shuddered and headed to the third room. Here the beasts were smaller, still spined and fanged but less armoured, more fleet-footed and with larger brain cases.

'These look smarter than the others,' she said, studying a creature the length of a large dog. Even dead, it made her feel uneasy.

'They've not long been killed,' said Flangers.

'They're thick-skulled. It could take them quite a while to die. Let's try the doors on the far side.'

They took the door furthest to the right. It was dark inside, but as soon as she entered Irisis could tell that this was different. There was no smell of blood, and the stench of fresh ordure was strong.