"Of course not, Doctor," oozes Brundle, casting Gregor a dirty look. The East German defector, Wolff, maintains a smug silence: I are above all this. "We're here to come up with policy recommendations for dealing with the bigger picture. The much bigger picture."

"The Builders," says Fox. "We're here to determine what our options look like if and when they show up, and to make recommendations about the appropriate course of action. Your background in, uh, SETI recommended you."

Sagan looks at him in disbelief. "I'd have thought that was obvious," he says.

"Eh?"

"We won't have any choice," the young professor explains with a wry smile. "Does a termite mound negotiate with a nuclear superpower?"

Brundle leans forward. "That's rather a radical position, isn't it? Surely there'll be some room for maneuver? We know this is an artificial construct, but presumably the builders are still living people. Even if they've got green skin and six eyes."

"Oh. My. God." Sagan leans forward, his face in his hands. After a moment Gregor realizes that he's laughing.

"Excuse me." Gregor glances round. It's the German defector, Wolff, or whatever he's called. "Herr Professor, would you care to explain what you find so funny?"

After a moment Sagan leans back, looks at the ceiling, and sighs. "Imagine a single, a forty-five RPM record with a centre hole punched out. The inner hole is half an astronomical unit — forty-six million miles — in radius. The outer edge is of unknown radius, but probably about two and a half AUs — two hundred and forty five million miles. The disk's thickness is unknown — seismic waves are reflected off a mirror-like rigid layer eight hundred miles down — but we can estimate it at eight thousand miles, if its density averages out at the same as Earth's. Surface gravity is the same as our original planet, and since we've been transplanted here and survived we have learned that it's a remarkably hospitable environment for our kind of life; only on the large scale does it seem different."