'Rouse out the slaves,' he said with a liquid chuckle.

Xervish Flydd lifted his head. His face was bruised all over, for the other prisoners had welcomed the fallen into their company.

'What do you want with us?' he said.

'We don't have enough bullock teams, so men must make up the difference. You're going in the first team, to serve as an example to all. The lash will teach you to do your simple duty, Slave Flydd.'

Flames blasted from a fissure in front of Tiaan. Liquid tar, hot enough to sting, dripped from the roof onto her head and shoulders; fumes burned tracks up her nostrils. A red glow lit up the tunnel behind her, for she was trapped in her walker, deep underground in Snizort. Though the lyrinx had repaired her severed spine with their flesh-forming Art, her legs were still too weak to stand on.

There was no field here, and the node was no longer visible. She reached down and felt the amplimet. It was still cool to the touch, thankfully, for heat could destroy such crystals.

The amplimet was powerful enough to draw on a more distant node, so she still had a chance. Tiaan tried to remember where other nodes might lie. In her long flight here in the thapter she had used many, and should have been able to recall them all, those memories were gone.

Everything was strange here; the ethyr was clotted with warpings the like of which she had never seen before. The amplimet seemed different, too. She wasn't sure how, but it was harder to use, almost as if it had grown stronger since the node exploded, or more wakeful and watchful. She did not like the feeling. Fighting down panic, Tiaan sought for a field and, at the very limit of her senses, detected a faint aura.

So far from the node that generated it, the field was tenuous, weak, fragile. She drew power into the controller. One leg twitched feebly but the walker did not move.

Dismayed, Tiaan made another attempt. That was better; she actually got one leg to take a step, though a wobbly, lurching one. She took another. Better still — she was remembering how to manage it.

Ahead, through cracks in the tunnel wall, the flames roared as if pumped by a distant bellows. They died away for the count of nineteen before roaring forth again. If she misjudged the timing, or went too slowly, she would be roasted alive.

Creeping as close as she could get, Tiaan waited for the next exhalation. It was sweltering here. She put her hand over the amplimet to protect it. The cracks flamed, then died to wisps. Now! She lurched the walker forwards and they flamed again, right at the controller. The impulse to jerk her hand away was overwhelming. She fought it, enduring the pain as she tried to make the machine go backwards. It shuddered but did not move.

The flames stopped. She tried to move forwards but that did not work either. Blisters were rising on the back of her hand. 'Move!' she screamed. The walker gave only a spastic twitch. Its front feet were stuck in tar which had softened in the heat.

Hot tar ribboned onto her shoulders. She bent the four legs as far as they would go, then straightened them all at the same time. Three legs pulled free, the other did not, and the machine began to topple. Tiaan threw her weight the other way and managed to save it, though it left her directly in front of the cracks. The next blast would burn her to a crisp. She could hear it coming, a breathy roar.

Flexing the legs again, she gave a mighty heave. The stuck leg pulled free and the walker shot forwards and up as the flames roared by. Tiaan felt the heat on her backside.

Further on, she went down into a hollow where heavy black fumes had pooled on the floor. As the walker crabbed through it lifted inky tendrils as high as her head. Eyes stinging, she lurched down the corridor, having no idea where she was going. Since the explosion, Tiaan could not remember Merryl's directions, and most of the wall lamps had gone out. She just kept moving because she could not remain where she was.

Creeping along, breathing through her sleeve, she thought she heard human voices coming from one of the branching tunnels ahead. 'Hello!' she yelled.

No answer. She moved to the intersection. Definitely voices, from the middle tunnel. She crept up through the gloom, turned a corner into a wider tunnel lit by a single lantern on a pole, and stopped.

Half a dozen people had their backs to her, staring at something that she could not make out. They looked like the human slaves the lynnx had kept here. The walker's legs clacked and they turned, squinting into the dark. She moved forwards and, with wild cries, they broke and ran. What was the matter? Tiaan realised, belatedly, that she must have made a terrifying sight, half human and half machine, and coated with droppings of tar.

'Wait,' someone yelled from around the corner. 'That's just Tiaan.'

The voice was familiar. 'Merryl?'

He appeared, carrying a lantern. She was so glad to see him. 'The tunnel's on fire, Merryl. I couldn't get through.'

'This passage leads to an exit but there's a construct stuck in the tar and we can't get past it.'

'A construct?' Tiaan edged forward curiously.

He caught her arm. 'Careful. The tar's sticky over there. I've sent people to pull shelves out of a storeroom, to stand on. We may be able to climb over the top.'

'Is there anyone inside it?'

'I don't know.'

The construct, which was just like her own thapter, though only half the size, was two-thirds buried in sticky tar. The former slaves, four men and two women, came panting up, carrying long planks, and began to lay them across the tar. The timber ran out just before the construct; they hurried off for more.

When planks had been laid all the way, they began to scrape the tar off with shovels and mattocks so they could climb over. Being unable to help, Tiaan waited where the tar was firm, working her wasted leg muscles until they hurt.

She had to be able to walk unaided. The planks were too narrow for her walker and she was wondering how she would get across when someone hissed, 'What's that?'

The work stopped. Tap, tap, tap came clearly from inside the construct.

Tiaan felt a spasm of fear. The Aachim had chased her halfway across Lauralin. If the ones inside were freed, they would come after her and these unarmed slaves could not stop them.

'Don't let —’ Tiaan broke off. She couldn't condemn those inside to suffocation.

'What's the matter?' called Merryl, who was stripped to the waist and covered in sweat. It was growing hotter all the time.

'Oh, nothing.' In her condition, Tiaan was afraid to trust anyone.

She watched as the tar was scraped off the top of the construct. It took ages, for it clung to the tools and they had to be cleaned every minute or two. Someone climbed up, holding the lantern aloft.

"Tunnel's collapsed further along,' the man announced. 'We'll have to find another way out.'

'All the other passages run back in the direction of the fire,' said Merryl.

The hatch of the construct was forced up, tearing the coating of tar into clinging strands. A head appeared in the opening. Tiaan edged back into the shadows, hoping it was some obscure Aachim who had never seen her.

It was Minis. Her heart began to hammer. She had sworn revenge on him and all the Aachim kind, but what was the point of that if they were all going to die?

Another Aachim climbed up beside Minis. Tiaan recognised her too, despite her haggard look. Tirior had also been in on the betrayal. Minis climbed down onto the boards and Tirior followed. A third person emerged, a short, stocky young man with a cap of dark hair that clung to the contours of his skull. Cryl-Nish Hlar, Nish. Her nemesis. If there was any man in the world she loathed as much as the Aachim, it was him.