On any planet where you could go up in the air easily, we’d be a sitting target. But on Harlan’s World, the normal rules don’t apply. Top mass limit on flying machines is a six-seat helicopter running an antique rotor-motor lift, no smart systems and no mounted beam weaponry. Anything else gets turned into mid-air ash. Likewise individual flyers in antigrav harnesses or nanocopters. The angelfire restrictions are, it appears, as much about a level of technology as physical mass. Add to that a height limit of about four hundred metres, which we were already well above, and it was safe to assume that the only way anyone would be approaching us was on foot up the path. Or climbing the sheer drop alongside, which they were very welcome to do.

Behind me, Sylvie grunted in satisfaction and I turned to see the cabin door flex itself open. She gestured ironically.

“After you, professor.”

The blue standby light flickered and blinked up to white as we carried our packs inside, and from somewhere I heard the whisper of aircon kicking in. A datacoil spiralled awake on the table in one corner. The air reeked of antibacterials, but you could smell that it was shifting as the systems registered occupancy. I shoved my pack into a corner, peeled off my jacket and grabbed a chair.

“Kitchen facilities are in one of the others,” Sylvie said, wandering about and opening internal doors. “But most of this stuff we bought is self-heating anyway. And everything else we need, we’ve got. Bathroom there. Beds in there, there and there. No automould, sorry. Specs I ran into when I was doing the locks say it sleeps six. Data systems wired in, linked directly into the global net through the Millsport University stack.”

I nodded and passed my hand idly through the datacoil. Opposite me, a severely dressed young woman shimmered into sudden existence. She made a quaint formal bow.

“Professor Serendipity.”

I glanced at Sylvie. “Very funny.”

“I am Dig 301. How may I help you?”

I yawned and looked round the room. “Does this place run any defensive systems, Dig?”

“If you are referring to weapons,” said the construct delicately, “I am afraid not. Discharge of projectiles or ungoverned energy so close to a site of such xenological significance would be unpardonable. However, all site units do lock on a coding system that is extremely hard to break.”

I shot another glance at Sylvie. She grinned. I cleared my throat.

“Right. What about surveillance? How far down the mountain do your sensors reach?”

“My awareness range covers only the site and ancillary buildings. However, through the totality of the global datalink, I can access—”

“Yeah, thanks. That’ll be all.”

The construct winked out, leaving the room behind looking momentarily gloomy and still. Sylvie stepped across to the main door and thumbed it closed. She gestured around.

“Think we’ll be safe here?”