The light came from a cross tunnel, from patches of some glowing substance in the hard, smooth walls. The tunnel was roughly circular in section, large enough for Nick to walk upright despite his height.
He whistled in amazement.
"Who built these?" he asked, for they had come several miles in darkness and now the lighted tunnel stretched away into the distance, a major engineering project.
"The Martians."
"How?"
"With their voras."
He wanted to ask her to explain, but she was examining some markings on the walls, combinations of triangles and curved lines that were obviously writing. She seemed to understand them, and Nick began to understand now how she and her father had evaded the Mec patrols so long. The leaders of the Martian Exploitation Company did not even suspect the existence of this extensive underground labyrinth.
"We're a long way from Klev's home," the girl declared. "The faster we get there the better."
"Why? What's the danger? The Mecs won't follow us down here?"
"Martians."