"Could something be interfering with the propulsion spells?" ventured Thomas timidly. "Making them send us off in the wrong direction, or something?"

     "The Gods alone know," replied Saturn wearily, rubbing his eyepatch with the heel of his hand. "There's so much magic aboard this ship, some if it must interfere even despite the shayen separation magics. As much magic as a small kingdom, contained in a metal ball twenty five yards across. We could all be turned into insects at any moment.”

     He paused while he took a deep breath to steady himself. “May I ask why none of you used the Helm of Farsensing in my absence? If you had, you would have seen for yourself where we actually were.”

     “Well, the thing is, there’s only the one helmet at the moment,” said Thomas, a little sheepishly. “I know that the eventual plan is for every member of the bridge crew to have his own, but at the moment there's just the one, which you seem to have claimed for yourself.” He smiled his embarrassment. “The rest of us were a little scared to touch it in case you got angry.”

     Saturn stared in disbelief. “What are you? A wizard or an infant?”

     "At least we can get home safely if we need to," said Timothy, trying to inject a cheerful tone. "We know the teleportation chamber works. The clay man used it."

     "Yes, we can all get home safely enough," the elderly wizard replied, "but if we can't control the ship's flight it becomes useless to us."

     "Could it be sabotage?" asked Prup Chull. "Perhaps the clay man did something else before attacking the Orb of Skydeath Protection."

     "That is certainly a possibility, my good friend," said Tana Antallan, "but why would it do such a thing? If it was confident that it could kill all of us without damaging the ship, why would it reduce the value and usefulness of the prize? Besides, if my understanding of the timescale is correct it had only a few minutes between leaving the soldiers and being interrupted by master Gown." He inclined his head to the younger wizard, who smiled gratefully back. "It simply did not have the time to do anything else. It must be a flaw in the ship itself, therefore. I suggest a series of test manoeuvres to see if we can identify the problem."

     "Why not?" replied Saturn with weary resignation. "Can't do any harm. Very well. We can use Kronos as a reference point. Let's try a little thrust directly towards it, say about a couple of thousand miles an hour. That'll give us plenty of time to swerve away if we find ourselves on a collision course."

     Rin Wellin, in the chamber above, heard the instructions and gave the necessary words of command to the Orb of Propulsion.

     Saturn had configured the mirror so that it showed a magnified view of the tiny moon as seen from the ship, as if they were seeing it through a telescope, and for a few moments they all gave sighs of relief as it began to swell before them, visibly growing closer. Maybe the shae folk had simply given the wrong instructions to the Orb, they were all thinking. It happened. Everyone was fallible, even the shae folk, and it could easily be that they had, in all innocence, said the wrong word, sending them in the wrong direction. If that was really all that had happened...

     Thomas imagined the shae folk sheepishly hanging their heads, the others subjecting them to a little good natured ribbing, maybe even Saturn himself, and then all of them having a good laugh as they remembered how worried they'd been. Their relief that the problem had just evaporated away. The Orb certainly seemed to be behaving itself now, at any rate...

     Then, with a sick feeling of horror, they saw the tiny moon begin to drift, ever so slowly, away from the centre of the mirror. "We're changing course," said Timothy softly, as if afraid that speaking too loudly would make the problem worse.

     They all turned to look at Tana, whose eyes widened in alarm. "We have given the Orb no new commands," he insisted, shaking his head wildly. "This is nothing to do with us."

     "Then either some kind of magical interference is responsible," said Saturn, "or we are under the influence of an outside force."

     "You mean we're under attack?" cried Thomas. "Is there another ship out there?"

     "The helm shows me nothing, but it's not impossible that someone has a way of hiding from magical detection. I don't believe it's an attack, though. Why just pull us off course? Why not destroy us, or board us while we're sailing with a skeleton crew? No, we are simply under the influence of a natural force of which we have been previously unaware, but what? What?"

     "Maybe..." began Prup Chull, but then he fell silent, a thoughtful look on his sagging, wrinkled face.

     "What?" demanded Thomas. "Have you thought of something?"

     "I don't know," replied the moon trog, staring straight ahead at the tiny moon that was now slipping out of sight. "It's just... Master Saturn, what was our exact position when we began to move?"

     "About three thousand miles behind it," replied the elder wizard, staring at him strangely.

     “Three thousand miles away in what direction?”

     “We were behind it. Following it as it circled the world.”

     “That would mean that, when we used the Orb to move towards it, we were in fact increasing the speed at which we were orbiting your world."

     "Yes. Do you feel that that is significant in some way?"

     "I don't know," Prup replied, looking confused. "Just a feeling, that's all. What would happen if..." He turned to look directly at the elder wizard. "Kronos orbits Tharia at a speed of about ten thousand miles an hour. What do you suppose would happen if someone gave it a push? If someone doubled the speed at which it was travelling through space?"

     "It would orbit once every four hours instead of once every eight hours," replied Thomas in a tone of voice that said this is obvious. Get to the point.

     "Would it?" said the moon trog, however. "Did you know that Lara and Luna move more slowly in their orbits than Kronos?"

     "They have further to go, so of course it takes them longer to travel the distance," replied Thomas with a tone of growing impatience.

     "No, you don't understand," said the moon trog with rising excitement. "They actually move through space more slowly. Look, Lara orbits at a distance of ninety eight thousand miles, that's an orbital radius of one hundred and three thousand miles, so it travels a distance of..." He scribbled rapidly on his pad. "Just over six hundred and fifty thousand miles. It takes six days to complete one orbit, so it travels at a speed of one hundred and eight thousand miles a day, or forty five hundred miles an hour. Over half as slow as Kronos. Do the same sums for Luna and you get a speed of... of twenty four hundred miles an hour. Do you see? The further out you go, the slower they move. The planets are just the same, and the free moons speed around Tharsol like, like..."

     "Like bees around a honeypot?" suggested Timothy with a smile.

     "Right!" agreed Prup, stabbing a finger at him. "But Rama creeps through space like a snail and Galluma the Mighty is the slowest of all. And the great worlds have moons of their own which follow the same rule. The further out you are, the slower you go."

     "So what are you saying?" asked Thomas, staring at him incredulously. "That if we speed ourselves up, some force pushes us down closer to Tharia?"

     "I don't know!" cried the elderly moon trog in frustration. "I'm just sure it's got something to do with what's happening to us!" He made an effort to calm himself down, aware that he was almost shouting. He continued in a softer voice. "It's something we need to look into."

     "What do you suggest?" asked Saturn with interest.

     "Continue the test manoeuvres," replied Prup eagerly. "Speed up and slow down in our orbit around Tharia and see what effect, if any, it has on our altitude. I would wager a great deal that our ship will follow the same rule as the planets and moons."

     "And how long will this take?"

     The moon trog shrugged. "A few days, perhaps. It can't be hurried, I'm afraid."

     Saturn nodded. "Very well, I leave it in your hands. In the meantime I have business back at the University. Contact me when you have reached your conclusions." He stood and, without another word, swept out of the bridge.

     The others stared after him in amazement, then turned to look at Prup Chull. "Well, Cap'n," said Timothy with a huge, toothy grin. "What do we do now?"

     The moon trog asked the cleric to hand him the Helm of Farsensing, which he placed carefully on his head. The weight of it was almost more than his feeble neck muscles could bear and he had to slide down in the wheelchair until his head was resting, rather uncomfortably, on the fabric backrest. Thomas frowned at his discomfort. They were going to have to work out something better than that, he thought in annoyance.

     "Orbmaster," said Prup Chull. "Let's start with a moderate thrust against our direction of motion, to slow us down. See what effect that has." He lifted the front of the helm enough to look out at Thomas. "Care to place a wager that we drift up into a higher orbit?"

     Thomas opened his mouth to answer, but suddenly froze as a thought popped into his head from nowhere. Back is down. If you try to go backwards, you go down. What did it mean?

     He froze, a look of vacancy on his face, he didn't know how long, until he was brought out of it by the feel of a hand on his shoulder. He looked up to see Timothy standing before him, looking concerned. "Are you all right?" he asked, peering searchingly into Thomas's bright blue eyes. "You went a bit strange for a minute there."

     "We'll go down," Thomas said, looking at the moon trog. "We'll drop down into a lower orbit."

     "What makes you think that?" Prup asked curiously.

     "I don't think it, I know it. When you slow down, you drop. I don't know how I know it, I just do."

     "But the lower orbits are reserved for faster moving bodies. You can't..."

     Thomas just waved a hand at him and he shut up. Thomas was worried and confused. Something was going on in his head and he had no idea what. "I think I need to lie down for a bit," he said, standing. "I suddenly feel very tired. Spellcasting does that to you sometimes. It all catches up with you at once. I just need a nap and I'll be fine."

     "You sure you're all right?" asked Timothy, touching the wizard’s forearm just below where the sleeve of his jacket stopped. Some followers of the Lady of Healing have the ability to sense a person's general state of health by skin contact, and in Timothy the ability was developed to an unusually high degree. What he sensed now confused him. Physically, the wizard was in very good health, but there was something, something...

     Thomas removed the cleric's hand with his own and they clasped hands for a moment. "I'm fine," he repeated. "A bit of sleep's all I need. I'll see you later." He slipped out of the room before anyone could ask any more awkward questions.

     He walked back to his quarters almost in a daze. Meaningless phrases kept going round and round in his head, an endless chant that wouldn't stop. Forward is up, up is back, back is down, down is forward, forward is up... Who had said those words? When? Where? He had a sense that the knowledge was right there in his mind, just out of reach.

     He tried some of the memory retrieval tricks he'd learned as an apprentice, but none of them worked. He sensed that the knowledge would come, though, if he just gave it time, and he desperately wanted it to come. Maybe it would bring some answers to what had been happening to his mind for months now. When he reached his cabin, therefore, he flopped down on his bunk and used another of the apprentice tricks he'd been taught to send himself straight to sleep.