Nona reached the convent buildings with at least two Noi-Guin hard on her heels, the furious tempo of their feet still muffled as if there were no circumstances under which the assassins could ever be considered noisy. Another cross-knife hit her, a razored punch into the back of her thigh.

A sharp turn along the alley between the laundry and winery building allowed Nona to pull the trick that had won her many races with her friends, kicking off the wall to make the tight corner without losing speed. She shot into the dormitory building up two flights of stairs, crashed through into the Holy dorm and leapt through the window above her study desk, shattering the shutters. She landed on the roof of the cold store across the way, rolling over the roof ridge with a scream as the cross-knife tore free from her shoulder. Two more rolls dropped her from the gutter and she hit the ground running, heading back towards the far end of the laundry. Her thigh was a white agony but she ran on with hardly a limp. Flaw-blades sliced into stone, allowing Nona to slingshot herself around a corner into the mangle room and then on through the washing gallery, down some steps and into the well room. Here laundry bags had been piled around the wall of the well, each tied by a length of rope that dangled down into the shaft. Without pause Nona jumped down the well, grabbing the ropes as she fell. The heavy sacks came with her, sliding some five or ten yards before choking together as the shaft narrowed. Nona jolted to a halt, cursing at the agony from her shoulder. A second later she let go and fell the rest of the distance.

She caught the stonework at the very bottom of the shaft with her flaw-blades and swung out over the pool into the cavern beneath the centre oak.

‘Hello?’ Spoken into the darkness. Her fingers found the hilt of the knife in her leg and she gasped despite herself. If she drew it out she would likely bleed to death. If she left it in then any venom still on the blade would continue to feed into her.

‘Nona?’ A weak voice, trembling.

‘You tell me. You’re the one who can see.’ A grin broke through Nona’s pain. She turned towards Ara’s voice.

‘Help me up.’ The rasp underlying each word spoke of a damaged lung. Broken ribs most likely.

‘You’re all wet,’ Nona said, finding Ara in the dark. She lifted her friend, trying not to put too much weight on her wounded leg. The pain now made it seem as if it hadn’t really hurt until she stopped running.

‘The novices lowered me into the pool like I told them to.’ Ara leaned against her. ‘Like you told me to tell them to. And they set up the bags …’ She straightened and gasped. ‘If someone wants to find us then a few sacks of dirty habits aren’t going to keep them out for long.’

‘No.’ Nona limped a step forward, bringing Ara with her. ‘So let’s not stay here long.’

The two nuns struggled on together, Nona wholly blind and navigating only by memory, Ara able to see but less sure of the route. Nona kept one hand pressing a cloth to the wound in her shoulder. The lead she had opened and the blockage in the well meant that the Noi-Guin would have to track her. Once they reached the undercaves, they would have Clera guide them. Nona let a little blood spill here and there. She wanted a trail Clera could follow rather than having to cede the lead to one of the assassins more skilled at tracking even though unfamiliar with the surroundings.

In a narrow passage a hundred yards on nausea overwhelmed Nona. She leaned against the wall and retched, spraying the ground before her.

‘Nona!’

‘I’m all right …’ She felt dizzy and sick. The black cure she had taken while running fought its battle with whatever venom had coated the Noi-Guin’s little knives. She bent double, hands on her thighs. Only her gasps, the rattle of Ara’s breath, and the drip, drip, drip of the caves broke the silence. And in her head Nona’s devils whispered fears to her. Fears so secret she had hardly acknowledged them even to herself.

Clera will betray you.

Arabella Jotsis has hated you from the start. To her you’re the same muddy peasant now as on the first day you arrived.

You’ll die down here, in the dark.

Tacsis, Jotsis, Namsis … all of them the same.

Yisht almost throttled you to death in these tunnels. You think you can escape eight Noi-Guin?

The Singular is with them. He’s worse than the other seven put together.

Leave the girl. She’s slowing you down.

‘Shut up!’

‘What?’ Ara stiffened.

‘No, not—’ Nona shook her head. ‘Never mind. Let’s keep moving.’

Nona limped blind through damp and narrow spaces with an untold weight of rock above her and a desperate need not to lose her way. In places both of them had to drag themselves across the floor like wounded animals. The knowledge that the most deadly assassins in all the Corridor were pursuing them proved unhelpful. Each of the killers would be wholly in their element, the ancient darkness flowing through their veins. Imagination filled the quiet between her breaths with soft sounds of stealthy approach. Several times Nona turned back along her path, determined to study the thread-scape and see how close the threat lay, only to tear herself away, unwilling to spend the time uncovering information that wouldn’t change her course of action. Ara made no complaint at any of these pauses, simply hung on Nona’s shoulder drawing slow painful breaths that scraped in and rattled out. Nona thought of Apple, lung-struck in the chaos of battle. With a sob she hauled Ara on.

Finally they reached Nona’s goal. She felt the pulse of the shipheart from within the rock wall in which she had sunk it.

‘Stand back.’ Nona dug her fingers into the stone as though it were clay and pulled forth the shipheart, her hands black around its alien light. Immediately the glow made familiar surroundings that had seemed so foreign when revealed only through her touch. The devils in her flesh retreated from the shipheart though it had been the one to spawn them.

‘You carried that here?’ Ara leaned back against the opposite wall, her face deathly pale, lips almost black.

‘I didn’t want to!’ Nona screwed her face up as the whispers inside her head became shouts. ‘I’m not Zole … I can’t heal us with it. I’m sorry.’

‘Hells,’ Ara muttered. ‘I’d rather hurt than touch that thing again.’

The fissure up which Nona had climbed lay just feet away. Before approaching it she retraced her steps ten yards down the passage, her heart pounding, expecting at every moment to meet a knife winging out of the dark. She pulled a thread from the stone, just one of the multitude that glimmered in her witch-sight. It told the tale of the rock from its constituents and formation to the carving of the channel by ancient waters. She drew it forth and knotted it to a thread in the opposite wall. A tremor of wrongness vibrated across the length of it then went still.

With her heart pounding, certain that the Noi-Guin would be on her at any moment, Nona went to the fissure’s edge. She exerted her rock-work skills, breaking stone from the fissure’s sides and at the same time reaching her rock-sense out along the passages that threaded like veins through the plateau. She could sense the silent bulk of the Glasswater: the sinkhole lay just a few hundred yards off, but even with the shipheart’s aid the water and bone of any human bodies approaching along the tunnels proved too small to register. Giving up on the search she dropped the shipheart, giving it a flick to send it rolling down the passage under her. It clattered off out of sight, far enough that no whisper of its light still reached up from the tunnel beneath. Nona allowed herself a sigh of relief at being free of the thing.