“Two days,” she echoed. “I’m exhausted already.”

Trey sighed and sat back against the tunnel wall. They would reach the old fledge seam soon, and then they would have to start working their way through that hollowness, that place once filled with fledge that had been mined by machines generations ago, taken topside by machines, transported across Noreela by machines. Try as he might, Trey could never imagine what these things had looked like working and moving. Although he’d seen images of them in books and on wall depictions back in the Church, they imparted nothing of what they had looked like alive.

“Did I ever tell you how they time the days topside?” his mother asked.

Trey smiled to himself in the dark.

“By the movement of the sun and moons. The sun rises and falls, that’s the day. The moons appear and disappear, that’s the night. The moons are sent away when the sun rises again. Two halves of each day are so different up there, one so bright and warm, the other so dark. And short? They’re so short!”

“Three days to one of ours,” Trey said. She had told him many times.

“Yes. Everything is over so quickly topside. You just get used to the heat of the sun on your face, and then it’s time to sleep, and then suddenly it’s time to rise again.”

Trey had never been up. He’d never felt the urge. He was terrified.

“We should go,” he said. “The old seam starts just along here. We can walk for some of it, Mother, but I think we’ll be doing some crawling too.” He did not repeat what he had suggested earlier—that they would simply hide in the caves—and neither did his mother. They had both known that there was no returning to the cavern, not for a long, long time. Trey felt tears threatening, at his mother’s bravery and his own fears, but he held them back. He did not want her to sense him crying. He needed to be brave.

They started into the old, mined fledge seam. At first it was little different from the tunnel they had just traveled, other than the floor being more uneven and the walls unsmoothed; the machines had never been afraid of sharp edges. Trey went first, uttering the little grumbles and clicks that echoed back and gave him an idea of the topography of the seam ahead. His mother followed on behind, one hand holding on to the loose belt on Trey’s jacket, the other held out to her side for balance. They made good progress. There was no hint of pursuit, and the sense of danger seemed to recede as they left the cavern farther behind.