'Then build your bomb,' Merlin said.

  'We need it sooner rather than later. That is where you come in.' Now Minla produced another sheet of paper, flicking it across the table in Merlin's direction. 'We have enough of the ore,' she said. 'We also have the means to refine it. This is our best guess for a design.'

  Merlin glanced at the illustration long enough to see a complicated diagram of concentric circles, like the plan for an elaborate garden maze. It was intricately annotated in machine-printed Lecythus B, the variant of the language used for technical communication.

  'I won't help you.'

  'Then you may as well leave us now,' Minla said. 'We'll build our bomb in our own time, without your help, and use it to secure peace for the whole world. Maybe that will happen quickly enough for us to begin redirecting the industrial effort towards the evacuation. Maybe it won't. But what happens will be on our terms, not yours.'

  'Understand one thing,' Jacana said, with a hawkish look on his face. 'The day will come when atomic weapons are used. Left to our own devices, we'll build weapons to use against our enemy below. But by the time we have that capability, they'll more than likely have the means to strike back, if they don't hit us first. That means there'll be a series of exchanges, an escalation, rather than a single decisive demonstration. Give us the means to make a weapon now and we'll use it in such a way that the civilian casualties are minimised. Withhold it from us, and you'll have the blood of a million dead on your hands.'

  Merlin almost laughed. 'I'll have blood on my hands because I didn't show you how to kill yourselves?'

  'You began this,' Minla said. 'You already gave us secret knowledge of the atom. Did you imagine we were so stupid, so childlike, that we wouldn't put two and two together?'

  'Maybe I thought you had more common sense. I was hoping you'd develop atomic rockets, not atomic bombs.'

  'This is our world, Merlin, not yours. We only get one chance at controlling its fate. If you want to help us, you must give us the means to overwhelm the enemy.'

  'If I give you this, millions will die.'

  'A billion will perish if Lecythus is not unified. You must do it, Merlin. Either you side with us, completely, or we all die.'

  Merlin closed his eyes, wishing a moment alone, a moment to puzzle over the ramifications. In desperation, he saw a possible solution: one he'd rejected before but was now willing to advance. 'Show me the military targets on the surface that you would most like to eradicate,' he said. 'I'll have Tyrant take them out, using charm-torps.'

  'We've considered asking for your direct military assistance,' Minla said. 'Unfortunately, it doesn't work for us. Our enemy already know something of your existence: it was always going to be a difficult secret to hide, especially given the reach of the Shadowlander espionage network. They'd be impressed by your weapons, that much we don't doubt. But they also know that our hold on you is tenuous, and that you could just as easily refuse to attack a given target. For that reason you do not make a very effective deterrent. Whereas if they knew that we controlled a devastating weapon . . .' Minla looked at the other Skyland officials. 'There could be no doubt in their minds that we might do the unthinkable.'

  'I'm really beginning to wonder whether I shouldn't have landed on the ground instead.'

  'You'd be sitting in a very similar room, having a very similar conversation, ' Minla said.

  'Your father would be ashamed of you.'

  Minla's look made Merlin feel as if he was something she'd found under her shoe. 'My father meant well. He served his people to the best of his abilities. But he had the luxury of knowing he was going to die before the world's end. I don't.'

  Merlin was aboard Tyrant, alone except for Minla, while he prepared to enter frostwatch again. Eight frantic months had passed since his revival, with the progress attaining a momentum of its own that Merlin felt sure would carry through to his next period of wakefulness.

  'I'll be older when we meet again,' Minla said. 'You'll barely have aged a day, and your memories of this day will be as sharp as if it happened yesterday. Is that something you ever get used to?'

  Not for the first time, Merlin smiled tolerantly. 'I was born on a world not very different from Lecythus, Minla. We didn't have land masses floating through the sky - well, nothing like what you have here, we didn't have global wars, but in many respects we were quite alike. Everything you see here - this ship, this frostwatch cabinet, these souvenirs - would once have seemed unrecognisably strange to me. I got used to it, though. Just as you'd get used to it, if you had the same experiences.'

  'I'm not so sure.'

  'I am. I met a very intelligent girl twenty years ago, and believe me I've met some intelligent people in my time.' Merlin brightened, remembering the thing he'd meant to show Minla. 'That stone you had your father give me . . . the one we talked about just after I came out of the cabinet?'

  'The worthless thing Dowitcher convinced my father was of cosmic significance?'

  'It wasn't worthless to you. You must have liked it, or you wouldn't have given it to me in return for my flowers.'

  'The flowers,' Minla said, thoughtfully. 'I'd almost forgotten them. I used to look forward to them so much, the sound of your voice as you told me stories I couldn't understand but which still managed to sound so significant. You made me feel special, Merlin. I'd treasure the flowers afterwards and go to sleep imagining the strange, beautiful places they'd come from. I'd cry when they died, but then you'd always bring new ones.'

  'I used to like the look on your face.'

  'Tell me about the stone,' she said, after a silence.

  'I had Tyrant run an analysis on it. Just in case there was something significant about it, something neither you, I nor your father had spotted?'

  'And?' Minla asked, with a note of fearfulness.

  'I'm afraid it's just a piece of whetstone.'

  'Whetstone?'

  'Very hard. It's the kind you use for sharpening knives. It's a common enough type of stone on a planet like this one, wherever you have tides, shorelines and oceans.' Merlin had fished out the stone earlier; now he held it in his hand, palm open, like a lucky coin. 'You see that fine patterning of lines? This kind of stone was laid down in shallow tidal water. Whenever the sea rushed in, it would carry a suspension of silt that would settle out and form a fine layer on the surface of the stone. The next time the tide came in, you'd get a second layer. Then a third, and so on. Each layer would only take a few hours to be formed, although it might take hundreds of millions of years for it to harden into stone.'

  'So it's very old.'

  Merlin nodded. 'Very old indeed.'

  'But not of any cosmic significance.'

  'I'm sorry. I just thought you might want to know. Dowitcher was playing a game with your father after all. I think Malkoha had more or less guessed that for himself.'

  For a moment Merlin thought his explanation had satisfied Minla, enabling her to shut tight that particular chapter of her life. But instead she just frowned. 'The lines aren't regular, though. Why do they widen and then narrow?'

  'Tides vary,' Merlin said, suddenly feeling himself on less solid ground. 'Deep tides carry more sediment. Shallow tides less. I suppose.'

  'Storms raise high tides. That would explain the occasional thick band. But other than that, the tides on Lecythus are very regular. I know this from my education.'

  'Then your education's wrong, I'm afraid. A planet like this, with a large moon . . .' Merlin left the sentence unfinished. 'Spring tides and neap tides, Minla. No arguing with it.'

  'I'm sure you're right.'

  'Do you want the stone back?' he asked.

  'Keep it, if it amuses you.'

  He closed his hand around the stone. 'It meant something to you when you gave it to me. It'll always mean something to me for that reason.'

  'Thank you for not leaving us. If my stone kept you here, it served a useful purpose.'

  'I'm glad I chose to stay. I just hope I have
n't done more harm than good, with the things I've shown you.'

  'That again,' Minla said, with a weary sigh. 'You worry that we're going to blow ourselves to bits, just because you showed us the clockwork inside the atom.'

  'It's nasty clockwork.'

  He had seen enough progress, enough evidence of wisdom and independent ingenuity, to know that the Skyland forces would have a working atomic bomb within two years. By then, their rocket programme would have given them a delivery system able to handle the cumbersome payload of that primitive device. Even if the rocket fell behind schedule, they only had to wait until the aerial land mass drifted over a Shadowland target.

  'I can't stop you making weapons,' Merlin said. 'All I ask is that you use them wisely. Just enough to negotiate a victory, and then no more. Then forget about bombs and start thinking about atomic rockets.'

  Minla looked at him pityingly. 'You worry that we're becoming monsters. Merlin, we already were monsters. You didn't make us any worse.'

  'That strain of bacterial meningitis was very infectious,' Merlin said. 'I know: I've run it through Tyrant's medical analyser. You were already having difficulties with supplies of antibiotics. If I hadn't landed, if I hadn't offered to make that medicine for you, your military effort might have collapsed within months. The Shadowlands would have won by default. There wouldn't be any need to introduce atomic bombs into the world.'

  'But we'd still need the rockets.'

  'Different technology. The one doesn't imply the other.'

  'Merlin, listen to me. I'm sorry that we're asking you to make these difficult moral choices. But for us it's about only one thing: species survival. If you hadn't dropped out of the sky, the Waynet would still be on its way to us, ready to slice our star in two. After you learned that was going to happen, you had no choice but to do everything possible to save us, no matter how bad a taste it leaves in your mouth.'

  'I have to live with myself when this is all over.'

  'You'll have nothing to be ashamed of. You've made all the right decisions so far. You've given us a future.'

  'I need to clear up a few things for you,' Merlin said. 'It isn't a friendly galaxy. The creatures that smashed your sky are still out there. Your ancestors forged the armoured sky to hide from them, to make Lecythus look like an airless world. The Huskers were hunting down my own people before I left to work on my own. It isn't going to be plain sailing.'

  'Survival is better than death. Always and for ever.'

  Merlin sighed: he knew that this conversation had run its course, that they had been over these things a thousand times already and were no closer to mutual understanding. 'When I wake up again, I want to see lights in the sky.'

  'When I was a girl,' Minla said, 'long before you came, my father would tell me stories of people travelling through the void, looking down on Lecythus. He'd put in jokes and little rhymes, things to make me laugh. Under it all, though, he had a serious message. He'd show me the pictures in my books, of the great ship that brought us to Lecythus. He said we'd come from the stars and one day we'd find a way to go back there. It seemed like a fantasy when I was a little girl, something that would never come to pass in the real world. Yet now it's happening, just as my father always said it would. If I live long enough, I'll know what it's like to leave Lecythus behind. But I'll be dead long before we ever reach another world, or see any of the wonders you've known.'

  For an instant Minla was a girl again, not a driven military leader. Something in her face spoke to Merlin across the years, breaching the defences he had carefully assembled.

  'Let me show you something.'

  He took her into Tyrant's rear compartment and revealed the matt-black cone of the syrinx, suspended in its cradle. At Merlin's invitation, Minla was allowed to stroke its mirror-smooth surface. She reached out her hand gingerly, as if expecting to touch something very hot or very cold. At the last instant her fingertips grazed the ancient artefact and then held the contact, daringly.

  'It feels old,' she said. 'I can't say why.'

  'It does. I've often felt the same thing.'

  'Old and very heavy. Heavier than it has any right to be. And yet when I look at it, it's somehow not quite there, as if I'm looking at the space where it used to be.'

  'That's exactly how it looks to me.'

  Minla withdrew her touch. 'What is it?'

  'We call it a syrinx. It's not a weapon. It's more like a key or a passport.'

  'What does it do?'

  'It lets my ship use the Waynet. In their time the Waymakers must have made billions of these things, enough to fuel the commerce of a million worlds. Imagine that, Minla: millions of stars bound by threads of accelerated space-time, each thread strung with thousands of glittering ships rushing to and fro, drops of honey on a thread of silk, each ship moving so close to the speed of light that time itself slowed almost to stillness. You could dine on one world, ride your ship to the Waynet and then take supper on some other world, under the falling light of another sun. A thousand years might have passed while you were riding the flow, but that didn't matter. The Waymakers forged an empire where a thousand years was just a lazy afternoon, a time to put off plans for another day.' Merlin looked sadly at Minla. 'That was the idea, anyway.'

  'And now?'

  'We breakfast in the ruins, barely remember the glory that was and scavenge space for the handful of still-functioning syrinxes.'

  'Could you take it apart, find out how it works?'

  'Only if I felt suicidal. The Waymakers protected their secrets very well.'

  'Then it is valuable.'

  'Incalculably so.'

  Minla stroked it again. 'It feels dead.'

  'It just isn't active yet. When the Waynet comes closer, the syrinx will sense it. That's when we'll really know it's time to get out of here.' Merlin forced a smile. 'But by then we'll be well on our way.'

  'Now that you've shown me this secret, aren't you worried that we'll take it from you?'

  'The ship wouldn't let you. And what use would it be to you anyway?'

  'We could make our own ship, and use your syrinx to escape from here.'

  Merlin tried not to sound too condescending. 'Any ship you built would smash itself to splinters as soon as it touched the Waynet, even with the syrinx to help it. And you wouldn't achieve much anyway. Ships that use the Waynet can't be very large.'

  'Why is that?'

  Merlin shrugged. 'They don't need to be. If it only takes a day or two of travel to get anywhere - remember what I said about clocks slowing down?' He had given the locals a thorough grounding in relativistic mechanics, although the time-bending consequences were still difficult for some of them to accept. 'You don't need to haul all your provisions with you, even if you're crossing to the other side of the galaxy.'

  'But could a bigger ship enter the Waynet, if it had to?'

  'The entry stresses wouldn't allow it. It's like riding the rapids.' Merlin didn't wait to see if Minla was following him. 'The syrinx creates a path that you can follow, a course where the river is easier. But you still need a small boat to squeeze around the obstacles.'

  'Then no one ever made larger ships, even during the time of the Waymakers?'

  'Why would they have needed to?'

  'That wasn't my question, Merlin.'

  'It was a long time ago. I don't have all the answers. And you shouldn't pin your hopes on the Waynet. It's the thing that's trying to kill you, not save you.'

  'But when you leave us . . . you'll ride the Waynet, won't you?'

  Merlin nodded. 'But I'll make damned sure I have a head start on the collision.'

  'I'm beginning to see how this must all look to you,' Minla said. 'This is the worst thing that's ever happened to us, the end of our history itself. To you it's just a stopover, an incidental adventure. I'm sure there were hundreds of worlds before us, and there'll be hundreds more. That's right, isn't it?'

  Merlin bridled. 'If I didn't care about you all, I'd have left twenty ye
ars ago.'

  'You very nearly did. I know how close you came. My father spoke of it many times, his joy when you changed your mind.'

  'I had a change of heart,' Merlin said. 'Everyone's allowed that. You played a part in it, Minla. If you hadn't told Malkoha to give me that gift--'

  'Then I'm glad I did, if it meant so much.' Minla looked away, something between sadness and fascination on her face. 'Merlin, before you sleep - do something for me.'

  'Yes?'

  'Make me flowers again. From some world I'll never ever see. And tell me their story.'