Patricia nodded. "Anything more specific, I'll get the shakes."

Farley patted her on the shoulder. "Must get back. Garry will be with you shortly.

"She entered the tent.

Patricia stood and smoothed down her jumper, then walked a few dozen meters across the sand. She bent down and ran her hands through the blades of a clump of grass.

The length of the corridor was so startling, compelling, that her breath slowed. It was spare, economical, incredibly beautiful. The even lighting, the gradually receding but nevertheless clear details; the sand, the bushes, the lakes and rivers flowing from southern cap condensation. . .

Despite what Farley had said, Patricia felt safe walking another dozen or so meters west. And having gone that far, still within a few minutes' run of the tent, it seemed no big deal to go an equal distance beyond. She reached the edge of the dwarf forest in ten minutes, then glanced back to orient herself to the tent and the ramp emerging from the cap tunnel.

The trees resembled scrubby pines, none more than two meters tall, their gnarled branches intertwined into an impenetrable thicket. She had never seen anything precisely like them on Earth, but their needles were similar to those on the Douglas fir Christmas trees her family used to buy before settling on an aluminum substitute.

She bent down to peer under the low canopy but saw no sign of life.

How strange, that the Stoners should take every living, moving thing with them. Stripping the Stone. Where did they all go?

That much was obvious, now. She could feel the compulsion each time she looked down the corridor. They headed into the infinite north, if the corridor truly was infinite.

"Patricia!" Lanier called from the tent. She jumped, slightly guilty, but there was no urgency or rebuke in his voice.

"Yes?"

"Work to do."

"On my way." She returned to the tent.

They sat by a folding table arranged under the awning. Lanier took a slate and plugged in a memory block, then set the apparatus between them. "You should have some idea now why we need you here. We have a couple of mysteries to figure out, and that"—he pointed down the corridor—"may not be the greater."

"I wouldn't think so," she said.

"I've already programmed a first-draft schedule for you. You'll get a tour of the third chamber city—concentrating on a library there. That city was called Thistledown, just like the Stone itself. It's a couple of centuries newer than Alexandria. And you'll make several return visits to the library in the second chamber. That'll take a week or two, just getting you started." He pointed to the slate and tapped a RUN button. Instructions scrolled down the screen. "Here's how to use the subways, schedules, and precautions. Obviously, I won't be able to guide you all the time, or even very often. Work piling up all over. And I'll probably be returning to Earth for a short while. During that time, you'll report to Carrolson. Most of the facts you need to know, regarding security, are in that block. Who to talk to, who not, protocol, that sort of thing. Farley, Wu and Chang are fine people, but be circumspect. Be circumspect around anyone who doesn't have the same privileges you do."