And dropped.

The sky was falling in on them. Then Marco, almost in hypnosis, turned the ship and there, spread out below like a bowl of jewels, was the flat Earth.

It was like a plate full of continents. A coin tossed into the air by an indecisive god.

The ship had come out perhaps 20,000 miles above it and out of vertical. Kin looked out at a hazy map of black land and silver seas fuzzed with moonlit cloud. There was what, for want of a better term -- how many people had mapped flat planets? -- a polar cap, hugging one side of the disc.

Moonlit? There was a moon, apparently a few thousand miles above the disc, and it shone. It couldn't be reflected light. There was nothing to reflect. And there were stars -- between the ship and the disc, there were stars. The shadowy oval lay inside a hazy globe. Marco translated what the machines were emotionlessly telling him. The disc was inside a transparent sphere 16,000 miles across, and the stars were -- 'that's what I said, Kin,' -- were fixed to this.

One edge of the disc glowed brighter. It flashed green fire, which ran around the rim until they were looking at a hole in space surrounded by green and silver flames. Then the ring grew a gem, and died as suddenly as it had come. The sun had risen. A tiny sun.

One machine said it was an external fusion reactor. It looked like a sun.

This is what I'll remember, thought Kin. The green fire at sunrise, because all around the disc there's a sea, and it flows over the edge in a waterfall 35,000 miles long and the sun shines through the falling water -- no wonder Jalo was mad.

Dawn rushed across the disc. Silver was the first to react. She giggled.

'He did call it a flat Earth, didn't he?' she asked. 'It was the truth, wasn't it?'

Kin looked. The continents had moved, it was true, and there didn't appear to be a New World at all. It was Earth down there -- she recognized Europe. Earth. And it was flat.

Marco put them into a fast orbit, and no-one left the cabin for three hours. Even Silver let a mealtime go past, and fed on curiosity instead.

They watched the waterfall slide past under high magnification. There were rocky islands, some tree-lined, overhanging the drop. It was a long drop -- 500 miles into a turmoil of steam. But the disc itself was only five miles thick. As the ship passed under the disc there was nothing but a space-black plain on the underside.

'Some humans used to believe the world was flat and rested on the backs of four elephants,' said Silver.

'Yeah?' said Kin. 'What did the elephants stand on?'

'A giant turtle, swimming endlessly through space.'

Kin tasted the idea. 'Stupid,' she said. 'What did the turtle breathe?'

'Search me. It's your racial myth.'

'I'd give a lot to know how the seas can keep on spilling over the edge.'

'Probably a molecule sieve, down there in the steam,' said Marco without looking up from the shouter screens. 'The plumbing is a minor matter, however. Where are the inhabitants? This thing is obviously an artefact, a created thing.'

'No-one's trying to contact us?'

'Just listen to my excitement.'

'I suppose you mean no. Perhaps it's as well. I keep thinking of all those weapons in the hold.'

'The thought seldom leaves my mind. Perhaps Jalo meant to hunt sea-serpents, but I think not. I cannot help thinking that anyone capable of building the artefact would hardly be bothered by any weaponry this ship could carry.'

'Perhaps the inhabitants are dead,' suggested Silver. Kin and Marco looked at each other blankly.

'Unlikely,' said Marco. 'More likely they've passed beyond the stage of gross physical existence. Maybe even at this moment they are screwing the inscrutable.'

'They're due for a big shock one of these days, then,' said Kin. 'This set-up must take vast amounts of power just to keep it going. The sun's orbit is all wrong. What keeps the seas from emptying? Why have they got their own private stars when there's real ones out here--'

'I can answer that one; said Marco. 'It looks as though the big sphere is only transparent from the outside. We can see in, they can't see out. Don't ask me why.'

'Do we land?' said Silver.

'How could we get in?' said Kin. Marco grimaced.

'That is easy,' he said. 'There's an eighty-metre hole in the shell. We passed it last orbit.'

'What?'

'You were busy looking at the waterfall and in any case it did not seem particularly important. No doubt the disc-dwellers have space travel.'

They hovered over the hole twenty minutes later. It was slightly elliptical, and the edges seemed to have been melted. It could have been made by careful jockeying of a ship with a fusion drive, thought Kin. Or a geological laser. Would a Terminus probe have carried one? Probably.

'We're still way above atmosphere,' said Marco. 'I hope the disc-dwellers aren't sore about people making holes in the sky.'

'We could offer to pay for repairs,' said Silver.

Kin wondered if that was a joke. Why would anyone shut themselves away from the universe like this? It didn't make sense, unless they were completely paranoid. If they weren't to start with they would be now.

'No,' she said out loud. 'They couldn't have built something like this if they were mad.'

'It looks like Earth, and Earthmen are mad,' Silver pointed out. 'I suppose humans haven't been doing a little secret world building?'

'No...' began Kin, and saw they were both looking at her slyly. 'I don't know,' she finished lamely. 'It certainly looks like it, I'll admit.'

'It certainly does,' said Marco.

'It does too,' agreed Silver.

'Don't breathe,' said Marco. 'There's just enough room. We're going in.'

The ship dropped through with a few metres to spare, and the proximity detectors shrilling. They were still going mad when Kin looked up and saw a ship speeding towards them.

It hit in one of the holds, buckling the hull and sending the sky wheeling crazily. Damage doors crashed into place and then the control room lurched again as it fell away from the ship under its own power, a self-contained emergency craft.

The damage to the ship was nothing to what happened to the attacker. It disintegrated.

Blue-green shards were spreading across the sky and, as Kin pulled herself up from the cabin floor, the screens were sparkling like glitter dust.

The inner door of the emergency airlock opened and Marco loped in, tugging at his helmet with two hands. Another one held a laser rifle, salvaged from the other half of the ship. The fourth held a long sliver of glass, gingerly.

'Looks like someone threw a bottle at us,' said Kin.

'Their aim was remarkable,' said Marco coldly. 'I can take us back to the rest of the ship, but it is hardly worth it. We've got no Elsewhere capability. I can't build a pinch field. Most of the contents of the hold are floating out there somewhere, and they were our weapons. The auxiliary systems are all working. I could probably fly us home on the ringrim motor alone.'

'Then all is not lost,' rumbled Silver.

'No, except that it would take about two thousand years. Even this bloody gun is useless. Someone thought it a safe idea to pack the main coil in a separate box.'

'So we land on the disc,' said Kin flatly.

'I was wondering when someone was going to say that,' said Marco. 'It'll be a one-way trip. This craft won't lift off again.'

'What hit us?' said Silver. 'I thought I saw a ball about ten metres across...'

'I've got a horrible feeling I know what it was,' murmured Kin.

'Yes. It was a weapon,' said Marco. 'I admit I find its complete destruction difficult to understand, but the fact remains that we had a stargoing ship. Now we have not. I intend to make one orbit before landing.'

Silver coughed gently. 'What,' she said, 'will we eat?'