Only Turk had been to Bustee before. The name, he said, was derived from a Hindi word for "slum." It wasn't a slum, but it was a greasy little road town on the edge of the Rub al-Khali, catering to traffic along the northernmost route to and from the oil lands. Cinderblock buildings and a few timber-framed houses; a store that sold tire gauges, maps and compasses, sunblock, cheap novels, disposable phones.

Three gas stations and four restaurants.

None of which Lise could see from the window of the motel room. The ashfall sifted down in gray, stinking curtains. Power lines down or transformers shorted by dust, she guessed, and repairs wouldn't be quick, not out here in low-priority-land. It was a miracle they had made it here at all, even in their big all-terrain all-weather vehicle. Someone from the motel office knocked at the door and handed out flashlights and a warning not to attempt candles or any kind of open flame. But the Fourths had packed their own flashlights, and there was nothing to see anyway, only dingy walls and patchwork wallpaper.

Lise kept a flashlight at hand for navigating her way to the bathroom when the need arose.

The boy Isaac slept, driven more by exhaustion than sedatives now, Lise guessed. The adults had huddled for conversation. Dr. Dvali was speculating about the ashfall in his persuasive and gently-modulated voice. "It might be a cyclical event. There's evidence in the geological record—this was some of your father's work, Miss Adams, though we never knew how to interpret it. Very thin ash layers compressed into the rock at intervals of ten thousand years or so."

"What does that mean," Turk asked, "it happens every ten thousand years? Everything gets buried in ash?"

"Not everything. Not everywhere. You find evidence of it mainly in the far west."

"Wouldn't it have to be a pretty thick layer to leave traces like that?"

"Thick, or persistent over a long period of time."

"Because these buildings aren't built to hold up anything much more than their own weight."

Roofs crushed, dust entombing the survivors: a cold Pompeii, Lise thought. That was chilling. But she had another thought. She said, "And Isaac—is the dustfall connected with what's happening to Isaac?"

Sulean Moi gave her a sad look. "Of course it is," she said.

* * * * *

Isaac understood it best in his dreams, where knowledge was rendered in wordless shapes and colors and textures.

In his dreams, planets and species arose like vagrant thoughts, were dismissed or committed to memory, evolved as thoughts evolved. His sleeping mind worked the way the universe worked—how could it be otherwise?