Dura and Rauc were working together in a corner of Qos Frenk's ceiling-farm. Dura was wearing the mandatory Air-tank, but she wore the veil pushed back from her face; and the heavy wooden tank thumped against her back as she worked. She had pushed her head and shoulders high into the stems of wheat, so that she was surrounded by a bottomless cage of the yellow-gold plants. She reached above her head with both hands, burrowing with her fingers among the roots of the wheat. Stems scratched her bare arms. Here was another sapling; it felt warm and soft, undeniably a living thing, a thin thread of heavy-nuclei material pulsing along its axis. Young Crust-trees were the most persistent danger to Frenk's crop, springing up endlessly despite continual weeding. The saplings — thinner than a finger's width — were difficult to see, but easy to pick out from among the wheat-stems by touch. She allowed her fingers to track along the sapling's length further up into the shadows of the wheat. She probed at its roots, which snaked up into the tangle of roots and plants which comprised the forest ceiling, and patiently prized them out.

It was dull, mindless work, but not without a certain satisfaction: she enjoyed the feel of the plants in her fingers, and relished deploying the simple skills she was learning. Maybe in some other life she might have been a good farmer, she thought. She liked the orderliness of the farm — although not the pressure of other people — and the work was simple enough to leave her mind free to wander, to think of Farr, of the upflux, and...

Rauc half-laughed. "Look at that. Dura, look... How strange."

Vaguely irritated at this irruption into her daydream, Dura dropped down from the inverted field. Emerging into the clear Air, she rubbed her hands free of dust. "What is it?"

Rauc hovered in the Air, Waving gently; she pointed downward. "Look at the vortex lines. Have you ever seen them behave like that before?"

Vortex lines, acting strangely?

Dura snapped her head downward and raked her gaze across the sky.

The vortex lines were shimmering — infested with so many small instabilities that it was difficult to see the lines themselves. At the limit of vision Dura could just make out individual ripples racing along the lines, like small, scurrying animals. And the lines were exploding upward, out of the Mantle and toward the Crust. Toward the farm. Toward her.

All of the lines were moving, as deep into the sky as she could see; the parallel ranks of them hurtled evenly out toward her.

There was something else, too: a dark shape far away, at the edge of her peripheral vision; it scored the yellow horizon with a pencil of blue-white light.

"Rauc," she said. "We have to move."

Rauc looked up at her, the thin, tired face beneath its veiled hat registering unconcern. "Why? What's wrong?"