Asman led him to the mural that occupied one long wall of the large, low-ceilinged room. The room itself was featureless, as were the men tending the machines. It could have been the security room of any Board-run world. But there was something about the quality of the air, even of the light, that suggested an underground vault - Ways in fact sensed the layer upon layer of shielding around him - and there was something in the confident, unthinking way that the Earthman Asman moved that suggested in which planetary crust the room was buried.

The mural was a brightly-lit tangle of coloured lines, circles and blocks of p-math, that shifted slightly as he watched.

'You've done well,' Asman said again. 'He's moved along the right equation.'

'As to that, how do I know? I just keep trying to kill him, just like the others. Do you want me to try on Band?'

'No, your next point of intervention should be...' he glanced along the rainbow lines '... oh, not till he visits those Creap. We've got contingency plans for that. It's all in the equation, anyway. We'll be hot on their heels then, if they have heels. The math says so. One more intervention when he gets to Laoth and we'll be in the Joker universe.'

Ways blinked slowly. 'Is this information I need to know?'

Asman returned his gaze. 'What do you mean by that?'

'Look,' said Ways, sitting down, 'you made me. Not you, precisely, but someone on Laoth or Lunar. They made me. I'm a robot.'

'That's not held against you. If we were Creap we'd have simply bred up a Creap with the required characteristics, in some vat. But you can't wamp up a man, so you ...'

'Okay, but I'm a robot, even if I'm a special one. I've got everything from toenails to offensive underarm odours, but that's all faked. So what does it matter what a robot knows?'

'You've made your point. Now, are you interested?' Asman was growing impatient.

'Certainly. Why doesn't he die when I kill him?'

'The universe alters.'

Shoot a man from point-blank range, so that your beam dislodges every organic molecule from hair to feet. All the rules postulate an outcome of, say, a mono-molecular mist, a few zips and geegaws on the floor, and a faint smell of burning. But there is always the outside chance. The stripper goes imperceptibly out of sync. Or you hallucinated that you pressed the stud, and didn't. In a shifting universe there is no such thing as a rock-hard certainty, only a local eddy in the stream of total randomness. Just occasionally the coin comes down on its edge, or doesn't come down at all.

'Dom Sabalos is likely to discover Jokers World in ...' Asman glanced at the far end of the mural... 'twenty days, Standard. We can't stop him. He's our first failure out of, oh, it must be several thousand now.'

'Two thousand three hundred and nine,' said Ways, 'I killed them.'

'They all had the right life equations. Any one of them could have made the discovery. His father, for example.'

'And now it isn't working," said Ways. 'We've found some history we can't change. And we're suspected, you know. Look at young Sabalos. All those precautions, on such a harmless world. The Sabaloses are a popular family. After the death of his father they must have felt that he was in danger, too, and not from a Widdershine. I don't think he was even told about the Jokers until he was out of childhood. Another thing. We are driving him to Jokers World.'

Asman rubbed his hands thoughtfully.

'We have considered that,' he said.

'If we hadn't made the attempts he'd probably still be on Widdershins. Instead he's flying around with a robot and a Joker expert - quite a good one, too, from what I've heard.'

Asman nodded. 'Of course, one doesn't have to travel to discover,' he said. 'However, what you say is true. We have been working on a contingency plan. If all else fails we can follow him.'

There was a heavy silence. Ways said quietly: 'To the dark side of the sun?'

'If there is no alternative, yes. Wherever it may be. According to our latest equations, that is what we will do.'

'So you are preparing for it?'

'Oh yes. Sometimes, robot, I get the horrible feeling that we live in a big ever-repeating circle where we do things because it is predicted that we will do things - all effect and no cause. We'll go, anyway, and we will go armed.'

Ways looked at the man, and around the long low room. For a moment he considered the possibility of a universe caught in a circle of predict-and-effect, the ultimate closed circuit, and wondered if the inhabitants would realize what they had done.

'That's not enough,' he said. 'Why isn't he dying?'

Asman shrugged. 'Would you believe the Jokers alter the universe just so that he can remain alive? That's the current favourite. Maybe they want him to discover their world. Maybe - and this one is our prime hypothesis - they are waiting to be discovered. Perhaps this is all necessary to jog him through slightly differing alternate universes into the one where the Jokers exist. That's an outsider, but worth considering.'

Ways was silent.

'That gives you something to think about, eh?'

He nodded. Then he pulled aside his cloak and made a few passes over his chest. A partition slid back and he extracted a small cage, hastily soldered together from power wire. Inside, a small rat-like creature, six-legged and pink, gyrated and yowled, spitting at Asman.

'His pet,' said Asman.

'I expect you knew about this,' said the robot.

'It's on the board,' he admitted. 'We didn't bother to go into details. So this is Ig. Strange little thing, isn't he?'

'It's an it,' said Ways. 'Ask me to tell you how they breed, and I'll answer loudly and with gusto. They eat everything, even artificial epidermi as it turns out.' He held up a finger, bitten to the alloy. 'I'm the latest expert on them. Widdershine fishers say they're the souls of drowned men, to which they may bear some resemblance. They're the third largest air-breathing creature that the planet has produced. Phnobes think they're lucky, and the fishers say that if one makes a pet of you it means death will never be lethal. It could be they have a rudimentary psychic sense, like dogs or Third Eye dragons. It's difficult to see why, since they have no natural enemies and they're something of a planetary totem. The bomb should be planted inside the rib cage, I suggest.'

'Bomb?'

'You plan that Dom should be killed after we've discovered the position of Jokers World. You didn't tell me that, by the way. I suggest that this is what you have in mind. This thing sticks to him. I can see it gets back to him.'

Asman covered the cage. 'As a matter of fact, we have considered something like that. Fine,' he added, with just a hint of nervousness.

While an underling spirited the cage away he added: 'You enjoy food?'

'To some extent the calories are a useful power supplement, as you know.'

So they went to The Dark Side of The Sun, a low mock-phnobic building built on and merging with the sand hills between the Joker Institute and the Minnesota Sea. It was one of many. The Institute had attracted a sizeable town, based on the Joker Industry, a limited amount of tourism and alien visitors. Most of the Earth tourists came to see the aliens and feel cosmospolitan, and the management of the Dark Side tried to cater for this. The walls were decorated with imaginative hologram murals - Creapii sun rafts drifting across Lutyen 789-6, a drosk eight-unit at a funeral feast, grim-faced gardeners fighting a rogue tree on Eggplant, Spooners doing nothing very comprehensible on an unknown ice world.

There were sculptures, too. The phnobic display was unconvincing and probably a fake, although the snow sculpture by an unnamed Tka-peninsular drosk was almost certainly genuine, and so was the... thing, difficult to describe or even to comprehend, that spun slowly around the ceiling, occasionally bumping the walls. The floor covering was an alive and semi-sapient B owd l er, on the payroll, and the serving robots were genuine Laothans. The Dark Side was in fact well-patronized by the more adaptable aliens, who appreciated its cooking and prized its uniquely Earth ambience.