Nona couldn’t believe it. How would Joeli even get her hands on … Nona remembered where she was. Joeli could have stolen some there and then. What to do? The time to run had gone, and in truth there had never been time to run, not after that first soft impact of the package hitting the ceiling.

Keep calm. Sister Apple’s first piece of advice. Easily said, hard to do. Panic would burn up the air in Nona’s lungs more quickly. Grey mustard spores had to be kept completely dry. They lost their effectiveness rapidly in damp conditions. In a fog they wouldn’t spread and would lose potency within seconds. In the moist air of the undercaves they might stay dangerous for five or ten minutes. But Sister Apple had taken great care to keep the stores chamber arid. It might be an hour before it was completely safe to walk around.

The mustard spores wouldn’t penetrate cloth in a hurry and Nona was well covered, but if she got up and started to run they would swirl up under her habit and likely find a way into her hood and down her sleeves. Nona had seen the scars on Sister Rock’s leg where she was exposed to the margins of a mustard cloud. The wounds were angry, red, and ugly. Sister Apple said the pain could last a lifetime. Which went a long way towards explaining Rock’s temper.

Nona’s lungs began to tingle with the first hint of the burn that would grow and grow, demanding that she draw breath. Her rock-work offered no solutions: even if she had the skills to do more than make shapes in the fire, she had no flame. Her marjal dominance over water and air was less dominance and more being able to ask the occasional small favour. Speed wouldn’t save her. Possibly she could walk the Path, but she felt too weak and the energies she would gain might wreck the room but they would be unlikely to destroy all the spores.

Frustration warred with raw terror. After all this time Joeli was going to win and Nona would die the worst of deaths alone in the dark.

Without hope she began to roll, keeping her legs tight together, depending on the sacks, over-habit and the skirts of her own habit wrapping tight around her ankles. She raised her arms to pin the hood around her face as best she could. The total darkness stopped her from knowing whether there were gaps through which the spores could reach her eyes. She would soon find out if there were.

Five or six rotations were sufficient to get Nona’s internal map of the cave spinning. She tried to roll slowly enough so that the sacks and her habit wouldn’t flap around her, but the air in her lungs couldn’t last forever. Already she wanted to take that breath.

Surprise at the sudden impact of her ankles against something unyielding almost made Nona inhale. A series of crashing sounds followed, Sister Apple’s precious ingredients taking the plunge. Nona buried any guilt under the certainty that an agonizing death waited in her immediate future. Already her ankles were burning. She pushed away images of a survival that left her scorched, her face a ruin, scalp pink and scarred, the shock and revulsion as her friends first saw her … Regol’s features stiffening, the smile falling from his lips.

An adjustment and another set of rolls brought a second collision. Another series of crashes followed. Panic wrapped itself around Nona’s lungs, squeezing tight. She didn’t know where she was, she couldn’t roll to the door. She would have to stand, exposing herself to the spores. And even as she began to rise she knew with cold certainty that before she found the door in the darkness, flailing around as the skin bubbled from her hands, she would have to draw breath, and then her lungs would start to perish. Nona had seen men die from grey mustard, she’d watched it through Kettle’s eyes deep within the Tetragode. She couldn’t end like that. Fear only consumed her air more swiftly but serenity had escaped her.

Gathering her courage, Nona rose and launched herself in the direction she hoped the door lay. With arms folded over her face she crashed into something that was not a door. A whole rack of shelves toppled to the ground with Nona tangled in the structure. Pots and packages rained down and each shelf seemed to break free of the frame as the thing fell.

Nona hit the ground hard and lay face down amid the sharp edges of the clutter. She had to draw breath. The whole of her body clamoured for it. Traitor muscles lifted her chest demanding air. She clamped her jaw, hammering the ground with her fists, refusing defeat. Spots of red light flashed in her vision, the beat of her heart became a drum, a thunder in her ears, the pressure built, beyond pain, beyond resistance. With a sob of despair she released the stale breath she had clung to so long, and hauled in a new one.

The burn hit immediately. Within moments Nona was rolling helplessly, coughing, choking, her eyes beginning to sting. Spluttering, the drool running from her chin, Nona gained all fours and crawled, direction abandoned to panic now. She banged her head against stone and sobbing she followed the wall around with blind hands. At last she found the wood of the door. It gave beneath her push and she tumbled out into the corridor.

Nona sat, wiping snot and slobber from her face. ATISHOO! An almighty sneeze shook her, ringing down the tunnel.

It took another moment to realize that it hadn’t been grey mustard. ‘Pepper!’ ATISHOO!

Apart from the echoes of Nona’s sneeze there was no noise.

‘Shit!’

Somewhere along the tunnel a door opened.

Nona leapt up. A whisper of light from the Shade classroom windows gave her direction and the edges of the corridor. She slapped a hand to the wall where she had carved a channel for the lock catch. A pulse of marjal enchantment and rock started to rain from the area in fragments. She hadn’t time to repair her work so she hoped to hide it instead. The damage could look like the work of hammer and chisel now.

She was running before Kettle’s shout rang out. She tore along the tunnel, bashed through the door into Shade class and dived the length of the window tunnel, escape now her only thought.

As her body flew towards daylight Nona clung to the moment, so fiercely that she seemed to inch through the air. She couldn’t climb. Kettle was too fast. She would reach the window and look up. But down was so much further …

Nona touched her hands to the wall to slow her at the exit … and dropped.

The cliff below the windows was near vertical. The fall was more than three hundred yards to wooded slopes that rose in the shadow of the Rock of Faith. Nona twisted as she fell. When the rock face threatened to scrape against her she nudged herself out by fractions with hunska-speed kicks. She dropped a hundred yards, now travelling so fast that it seemed rapid even in the midst of her own swiftness.

Nona couldn’t use her flaw-blades, not in sight of the window. Her descent would be too slow and the marks left behind would make it obvious who had been there. Another fifty yards of wall sped by. The tree tops approached at frightening velocity.

At the last moment Nona drove her flaw-blades into the rock with one hand, at first just the tips, letting her arm take the strain of deceleration. She used the other arm to angle her blades against the stone and keep her body clear. Without that precaution she would have left half her flesh in a thirty-yard smear reaching to the ground. The force on her arm grew and grew with each passing yard, threatening to pull her shoulder from its socket. She slowed from a hurtle to a rush. The thump with which she hit the mossy boulders piled around the tree trunks at the Rock’s base was the kind you hobble away from cursing, rather than the kind that was both wet and crunchy.