But no, she said; Vox was designed to travel through inhospitable or changing environments all along the Ring of Worlds. All the worlds in the Ring were habitable, but conditions varied from planet to planet; the archipelago’s food sources had to be protected from changes in the length of days or seasons, wild variations in temperature, greater or lesser degrees of sunlight or ultraviolet radiation. Over the long term, aboveground agriculture would have been as impossible as raising crops on the deck of an aircraft carrier. The forest here was lush, but that was because Vox had been anchored in hospitable climates for most of the last hundred years. (“That might change,” Treya said, “if we cross to Earth.”) Originally these islands had been bare slabs of artificial granite; the topsoil had accumulated over centuries and had been colonized by escaped cultivars and windblown seed from islands and continents on two neighboring worlds.

“Can we get down to the farmland?”

“Possibly. But it wouldn’t be wise.”

“Why—are the farmers dangerous?”

“Without the Network, they might be. It’s difficult to explain, but the Network also functions as a social control mechanism. Until it’s restored we should avoid untutored mobs.”

“The farm folk get rowdy when they’re off their leash?”

She gave me a disdainful look. “Please don’t make facile judgments about things you don’t understand.” She adjusted her pack and walked a few paces ahead of me, cutting short the conversation. I followed her down the hillside, back into the shadow of the forest. I tried to gauge our progress by marking the relative positions of the black towers whenever we crossed an open ridge. I calculated that we might reach the windward shore in a day or two.

The weather turned sour that afternoon. Heavy clouds rolled in, followed by erratic winds and bursts of rain. We marched on grimly until we began to lose daylight; then we found a sheltering grove and stretched a sheet of waterproof cloth between the closely woven branches to serve as a shelter. I succeeded in getting a small fire going.

As night fell we huddled under the tarp. The air reeked of woodsmoke and wet earth. Treya hummed to herself while I heated rations. It was the same song she had been humming in the aircraft before it was destroyed. I asked her again how she had come to know a ten-thousand-year-old popular song.

“It was part of my training. I’m sorry, I didn’t realize it was bothering you.”

“It’s not. I know that song. First time I heard it I was in Venezuela, waiting for a tanker assignment. Little bar there that played American tunes. Where’d you hear it?”

She looked past the fire, out into the dark of the forest. “On a file server in my bedroom. My parents were out, so I cranked it up and danced.” Her voice was faint.

“Where was this?”

“Champlain,” she said.

“Champlain?”