'OK. We'll do it the hard way.'

There was just something about the voice that made Marco loose his grip on the handle. Thus it was that, when the knife popped out of existence, it merely stripped the flesh of his palm instead of taking his hand off at the wrist.

Methodically he gripped his wrist to stop the blood flow, and let the pain batter outside his brain. He was still staring at the wound when a rush of air and a thump made him look up.

Something long and bloody was lying on the floor beside Silver. And the shand's arm was moving slowly. It fumbled around the meat, gripped it, pulled it dreamily to a mouth strung with saliva.

Silver ate.

'Where are we?' said Marco at last.

Kin's voice said, 'I'm not entirely sure. Are you OK?'

'I should like a drink. And some food. You had me slice the shand to get a protein sample?'

'Yes. Don't move.'

Something like a squashy bulb of water appeared beside Marco, and bounced limply on the floor. He picked it up and bit into it with shameful haste.

'Food now,' said Kin. Another bulb, filled with red sludge, rolled obscenely across the floor. Marco tried it. It tasted like solid boredom.

'It's the best I can manage,' said Kin. 'About the only damage you did was upset the disc master's dumbwaiter circuits. I've got rpbots repairing them, but until then the menu can just about manage to be unexciting.'

'Silver has fared better,' said Marco indistinctly.

'I told you I hadn't got time for niceties' said Kin. 'She's eating shand, cultured from her own cells. Don't ask me how it was done in seconds, I only gave the order. It might be an idea not to tell her, though.'

'Yes. You are in a position of influence?'

'You could say that.'

'Good. Get me out of here!'

There was a pause. Then he heard Kin say, 'I've been giving a lot of thought to that.'

'You've been giving a lot of thought to it?'

'Yes. I've been giving a lot of thought to it. You're in a sort of hold-for-study chamber. There's no way in or out except by teleportation, and if you knew what I know about that you'd rather stay in there and starve. I daren't cut in in case you're harmed. So, all things considered...'

A long shape exploded into being a metre from Marco, and landed heavily. He picked it up and looked at it suspiciously.

'It looks like an industrial molecule stripper,' he said.

'It is. I suggest you use it with caution.'

Marco grimaced in the hellish light and pointed the thing.

A section of chamber wall became a fine fog. He switched off hastily, and looked round for Silver.

The shand was kneeling, holding her head.

'How do you feel?' said Marco, in a concerned tone. He held the stripper lightly, not quite pointing it at Silver. The shand squinted at him vaguely.

'Odd things been happening...' she began.

Marco helped her to her feet, a more or less token gesture since she weighed ten times his weight -- and he needed one hand to keep the stripper not quite pointing at her.

'Right now, can you walk?'

She could stagger. Marco peered out of the chamber, into a dimly lit tunnel. Two small cuboid robots were fretting over the still-settling dust of the wall. He glanced back at Silver, and opted to point the stripper's flared nozzle at a questing waldo.

'Lay off the hardware,' said the robot, backing away.

'Kin Arad?' said Marco.

'Marco, that weapon is for your own peace of mind. But if you use it, I'll rip your arms off from here. And I can.'

Marco considered this for several moments, while Silver climbed laboriously out of the chamber. Then he shrugged with all four shoulders, and let the weapon thump on the floor.

'Monkey logic' he said. 'I'll never understand it.'

'I thought you thought you were human' said the robot with Kin's voice.

'So? All the thinking in the worlds doesn't change some things.'

'Cogito ergo kung,' said the robot. 'Follow me, please.' They fell in behind it as it rolled off along the runnel.

An hour later they were still walking. They had crossed wide metal chasms on lattice bridges and crouched in alcoves as giant machines thundered down side-tunnels. On one occasion the little cube had beckoned them to follow it on to a lift platform. At the next level down the lift had stopped again and a dozen humming golden cylinders had drifted on, smelling of ozone.

They followed narrow walkways between topless towering machines, which boomed.

'Krells' said Silver.

'Huh?'

The shand grinned. 'Didn't you ever see "Forbidden Planet"? Human movie. They remade it five, six times. I had a walk-on part in one, before I went to college.'

'Can't say I recall anything.'

'... I had to thump doors, mostly, and roar... had to share my dressing room with the robot, too. He was human.'

'A human robot?'

'The rest of the cast were actor-robots, you see. But there was this robot in the plot, and they couldn't find a robot who could act... robot-like. They had to hire a human. There was a very impressive scene inside a big machine built by the Krells, I think it was. Just like this. Krells, you understand, being fictional creatures invented for the purposes of the movie...' Silver broke off when she saw Marco's face.

He sighed. 'We have been around humans too long, you and I,' he said. 'We have been tainted by their madnesses.'

'I thought you were brought up on Earth? Are you not legally human?'

'My race papers are up there in the rest of the ship. Big deal.'

Silver grunted. 'Consider yourself a cosmospolitan, then.'

'What does that really mean, my friend?'

'It means the voluntary subjugation of one's racial awareness in the light of the basic unity of sapient kind.'

Marco growled. 'It doesn't mean that at all. It means that we learn to speak languages that monkey tongues can handle, and we get along in their world. Ever see a human act like a shand, or a kung?'

'No' Silver conceded. 'But on the other hand, Kin Arad is free and we were imprisoned. Humans always take the lead. Humans always get what they want. I like humans. My race likes humans. Maybe if we didn't like humans, we'd be dead. What's that?'

Marco followed her gaze. Half a mile away a tower loomed above the city-sized machines. It seemed to be made of giant balls stuck one atop another, and it glowed dull red. Silver pointed out the robots that clustered on the gantries that surrounded it, but Marco had to be content with a vague, eye-watering impression of something huge and ominous.

'A giant coffee percolator?' he hazarded.

Silver shouted at the little robot, which had rolled on ahead. It reversed neatly.

Silver indicated the stack of spheres that disappeared into the roof of the cavern.

'Basically' it said in Kin's voice. 'It's a simple device for heating rock to melting point and ejecting it under pressure.'

'Why?' said Marco.

'Volcano,' said the robot.

'All that,' said the kung, 'to give the disc volcanoes? Madness!'

The robot rolled away.

'You say that now,' it said. 'You wait until you see the earthquake machines.'

The journey under the disc took two days, as far as Marco and Silver could calculate. Sometimes they rode, crouching on flat trucks that glided along low tunnels with agonizing slowness, but more often they walked. Climbed. Inched along ledges. Ran like hell across switch yards, where sub-disc machines shunted and thundered on errands of their own.

Sometimes they came across dumbwaiters, perched incongruously in the whirring underworld. They had a new look, unlike their surroundings, which were worn. Well looked after, carefully maintained, but worn.

Marco raised the subject while they were sitting with their backs against a dumbwaiter.

'I know,' he said. 'If the disc people had an industrial revolution and then took a look at the" underside of their world, it'd scare the life out of them.'