THEY ENCOUNTERED A nest of stingers. There were only a few and they were small, no bigger than a man’s fist. And because they surprised the creatures, Trey was able to unsheathe his disc-sword and slice most of them down before they even had a chance to attack. The surviving stinger came clicking at them, aiming for Trey’s mother, but Trey kicked out at where he felt the thing passing through the air, knocked it into the stone wall and struck it down with the disc-sword. Sparks flashed, and in their brief light he saw the creature dying in a splash of its own blood.

They moved on. Trey was pleased that he had seen them through this danger, but it only went to remind him that there would be more challenges ahead. And not all of them would be stingers.

TIME TURNED THEIR escape into a long, painful haul instead of a panicked flight. They were both still conscious of the danger behind them, but the effort of navigating the seam occupied most of their thoughts. They had already made their way through one narrow passage—at least three hundred steps long—in which Trey’s mother had almost ground to a halt, too exhausted to pull herself through. He had tied his belt beneath her arms, hauling her after him like a mule pulling a fledge-laden cart.

Five hundred steps after this narrow stretch, Trey began to notice something in the air. A smell. The smell of people.

And beneath it, so distant as to be almost imaginary, the tang of blood.

“How long have we been moving?” his mother asked.

“A shift,” Trey said.

“A topside day,” she muttered. “I need to sleep, Trey. Very soon, I’ll need to sit and sleep. Are the Nax following? Do you think they have our trail?”

Trey sniffed and knew that there was a menstruating woman in the group that had come this way before. For a hopeful moment he thought that could be the blood he sensed, but there was something else. He kept up the pretense, though he knew it was false.

He had chewed a finger of fledge a few hours before. He had cast his mind back several times since then, searching, watching the way they had come, to see if anything was following. Clumsy though this casting was—he was doing it on the move, trying not to let his mother know what he was doing—he was certain that the psychic picture he drew of the empty seam behind them was true.

“Nothing’s following us,” he said, and his mother breathed a heavy, heartbreaking sigh of relief and exhaustion. “But, Mother, someone has come this way before us.”

She sniffed at the air for a few seconds, an old person’s heavy, unsubtle inhalation. “I smell nothing,” she said. “I used to have a nose like a cave rat, though I know I’m old now. Are you sure?”