‘Water,’ he croaked, tongue rasping over his lips. ‘Please.’

The begging made her think less of him. Nish had always been strong. Now he was weaker than her and she felt nothing but contempt. ‘Come down.’

‘The blades will cut me to ribbons.’

She hoped so. Ullii wanted to see his blood run free. ‘Jump!’

Nish considered all possible ways down, biting his sooty lip. ‘I can’t.’

Ullii had always resisted using her initiative. In the long years when the only thing she’d wanted had been her brother back, it had been easier to drift. Now the desire for retribution was so strong that it seared her.

She moved around to the next embrasure, out of sight from below. Taking her boots out of her pack, Ullii put them on then climbed onto the sill and hurled her pack up into the middle of the chamber. The fragile glass sang as it smashed and, with a tinkling roar, the central part of the network fell to the floor. She wove between the remaining spears, glass crunching under her soles, and eased her head over the sill on the yard side. Several guards had looked up at the sound, but only briefly. Pieces were falling off the tower all the time.

Nish was staring down at the gap. The pack had carved an elongated scar through the glass spears, though it wasn’t much wider than a human body.

‘Can you throw the pack again?’ he said.

It lay under a network of quivering spears, so precariously perched that a breath could have dislodged them. She shook her head.

Nish pulled himself along the supporting rods, choosing the spot carefully. He couldn’t drop – he had to throw himself through at just the right angle and, even had he been fit and strong, that would not have been easy. His hands were shaking. He rubbed his palms down his trousers, coating them with greasy soot. He tried to rub it off again but only smeared it everywhere. Nish gripped a rod, lowered himself until he was hanging full stretch, and began to sway back and forth.

Ullii could see the fear on his face but it no longer gave her any pleasure. Nothing gave her pleasure any more. She pulled out the knife, just to be ready.

‘What are you doing?’ he said, hanging motionless.

‘You killed Myllii.’

‘Myllii?’ he whispered dazedly.

Surely he hadn’t forgotten? He truly was a monster. ‘I’m going to kill you for that, Nish.’

He closed his eyes, which turned his face into an ebony mask, then opened them with a flash of white. ‘I’m sorry. It was an accident. He just reared back –’

‘It’s too late to say you’re sorry now,’ she whispered, overcome by memories still vivid and clear.

‘Ullii,’ he begged. ‘Please.’

‘Too late. Too late.’ She turned away, the blade hanging down. Ullii couldn’t look at him. Why was he saying it now? Why not back then, when it had mattered?

‘What about our baby?’ croaked Nish. Sooty flakes of skin broke from his lips and drifted upwards in the rising air. ‘Would you kill our little baby’s father?’

‘There is no baby!’ she said in a thin scream. ‘Yllii is dead and that’s your fault too!’

FOUR

Nish’s hand slipped and he flailed about wildly before getting another grip. ‘Yllii?’ he rasped.

‘Your son!’ It was an accusation – how could you not know his name? And an attack – it’s your fault.

‘My son?’ That threw him. His lower lip trembled. ‘Dead? How?’

How could he not know? Having lived Yllii’s death every possible way over the past four and a half months, she found Nish’s ignorance incomprehensible. It didn’t occur to her that he had no way of knowing these things. ‘You killed him!’ Ullii shrieked, half-mad with rage and grief.

Nish clung desperately to his perch. ‘You ran away, Ullii, and I couldn’t find you. I don’t know what happened from that day to this. But whatever happened to our son, I wasn’t there.’

‘You weren’t there,’ she whispered. ‘You were never there when I needed you, Nish. You didn’t care.’

‘I wept tears of blood for what I’d done to Myllii but I couldn’t undo it. Please, Ullii. What happened to our son?’

She swept the blade through the air. ‘Come down.’

‘Put the knife away first.’

She gave a half-hearted slash, screwed her eyes up, then laid the knife on the floor among the shattered glass, within easy reach. Nish would come down. He had to know what had happened to his son and it gave her the upper hand. At least he cares about Yllii, she thought, even if he hates me.

‘Come down, Nish.’

She studied him from under her eyelids. He seemed to be weighing her intentions. Now he began to swing his legs, trying to line himself up with the gap. Ullii could have done it with her eyes closed but he lacked her natural dexterity, and that pleased her selfish little soul. It wasn’t often that she felt superior.

Nish sucked in a breath, swung, and threw himself at the gap.

Before he let go, Ullii knew he’d miss. He’d swung out a little too far, a fraction too hard. His legs went through the gap but his body wasn’t lined up properly and he was heading straight for a pair of razor-sharp blades.

Nish jerked backwards and twisted sideways at the last instant, and his torso passed through safely. He whipped his head back, the blade shaved a clump of hair off the left side, nicking his ear, then he was through, all but his flailing left arm. It went side-on into a blade, cutting a deep gouge in his forearm before the glass broke. Blood spurted up as he slammed into a sloping slab of stone that was mercifully free of glass.

He didn’t move for a second or two. Blood pumped straight up from his forearm, coating one of the blades above him before dripping all over his face. Moving painfully, he got a thumb to the artery and the flow stopped. He looked up at her, the blood still dripping on his face, and across at the knife. She did too.

Ullii still planned to kill him. She took up the knife but Nish didn’t move. Blood welled out under his thumb and he pressed harder. She hated him for all that had happened to her since she’d been taken to the manufactory a year ago. Because of him she was alone in the world. She had no brother, no son, no friends, and now the lattice, her last resort and only comfort, had gone away. She didn’t know how to get it back.

‘I didn’t know Myllii was your brother,’ Nish said quietly, his voice barely audible over the singing of the blades in the wind. ‘I thought he was attacking you. Or holding you so the soldiers could carry you off to the air-floater.’

He looked ghastly, with his face and arm drenched in blood, and the rest of him covered in soot and flaking skin. She wavered.

Nish went on. ‘I told Myllii to stop but he reared backwards and the knife went straight into him. I’m so very sorry.’

Ullii closed her eyes. She was back at the campsite, holding Myllii and feeling his shock as the knife slid into his back. Tears welled out through her eyelids like drops of blood from a wound. Had Nish said that? She couldn’t remember – she’d been too overcome with joy at finding her twin after so many years of searching.

Nish could be lying. He’d used her before and he was, after all, the son of his father, Jal-Nish, the worst man Ullii had ever come across. She’d been a good judge of people once, but Ullii couldn’t tell about Nish any more.

‘What happened to Yllii?’ he said softly.

You killed him too, she wanted to scream while stabbing Nish to the heart. Ghorr had told her so, many times, and so had Scrutator T’Lisp, the wicked old woman who had trapped Ullii with Myllii’s binding bracelet. They’d told her that Nish was evil incarnate and had to be destroyed. Ullii had believed them at the time, and for a long time after, but looking back on her months in Nennifer she began to doubt. Chief Scrutator Ghorr was a monster whose handiwork she’d seen many times in Nennifer, and on the long journey here. He’d ruined Fiz Gorgo, killed dozens of innocent people and planned to torture the rest of them to death. And she had helped him, and betrayed every one of her former friends, so what did that make her?