They hadn't gone much further before the nature of the illumination changed. The natural sunlight channelled down through light pipes from the surface stopped to be replaced by glowbottles, their light harsher and greener, and from time to time they came across teams of moon trogs applying more activating fluid from large tanks carried on their backs. They must have passed the maximum depth through which they could thread optical fibres through the rock, Thomas assumed.

     They weren’t going all the way to the centre, though. The gravity grew less as they descended, and at the centre there was none at all. Some gravity, no matter how small, was useful, though. It kept the air clear from all the stuff that would have drifted around in it otherwise. The moon trogs’ main residential centres were about halfway down, therefore. An easy travelling distance from the surface.

     They stopped to rest again after one complete light dark cycle, sleeping in a side tunnel, by which time they estimated they'd travelled about fifteen miles and were five or six miles below the surface. The cavern had a neglected look to it, as if it had been years since anyone else had been there, another clue that the moon trogs went all the way from the surface to the residential regions in one go. Once again, the clumsily moving Tharians had slowed their escort to a fraction of the speed at which they normally travelled.

     The three wizards could also sense the gradual lessening in the intensity of ambient magic around them as they descended, as they had on their way down to the Underworld, the immense thickness of rock above them shielding them from the raw magic falling from the sky, and they knew they’d be unable to regain their magic until they returned to the vicinity of the surface. This bothered Thomas, but not as much as the idea of what being so far underground might be doing to Lirenna. She seemed okay, though, and he supposed that the knowledge that sunlight and greenery weren’t too far away was an invaluable tonic to her.

     The tunnel went on and on, until they began to think they must be about to emerge on the far side of Kronos, but eventually they began to see more side tunnels leading off above, below and to either side with moon trogs busily coming and going in all of them, and they knew that they were finally getting close to a major population centre. Their escort, to give them the politest possible name, led them off into one of the side tunnels, and soon they were once more surrounded by green, growing plants, growing in the light of the glowbottles.

     Unlike the tunnels around Kronosia, though, which were filled with untended wilderness, the greenery in these tunnels bore more of a resemblance to parkland or gardens, with bright flowers and neatly pruned shrubs growing amidst neatly mown lawns which covered walls, floor and ceiling. They passed several caverns on all sides, all up to a hundred yards long and fifty yards wide, full of life and greenery, each cavern containing half a dozen doorways leading into the moon trogs’ homes themselves, carved out of the surrounding rock. The caverns seemed to be their gardens, their communal meeting areas, where the children of several families met to play together under the watchful gaze of a couple of adults. It seemed to be an almost idyllic existence, and they couldn’t help but notice the contrast between life here and in the violent and oppressive human city. Only the guardsmen escorting them made them doubt the absolute perfection of moon trog society. What do they do when they’re not escorting humans? wondered Thomas. If they have guardsmen, then they must have crime of some kind.

     A few minutes later they arrived at a cavern rather less attractive than the others, with fewer glowbottles and in which the plants grew spindly and stunted in the half light. A flock of rats half jumped, half flew out of their way as they entered, disappearing into the undergrowth, and some of the doors leading into moon trog homes stood open, telling them that they were unoccupied. One of the homes was still in use, though, and seemed to have been converted into a prison, and it was to this one that the Tharians were led by their ‘escort’.

     “The Dallak will see you in two lights,” said the leader of the guardsmen. “Until then you will wait here. If you need anything, tell the keeper and he’ll see that you get it.” He indicated a moon trog dressed in whole body leather armour and with a bunch of keys hanging from his belt.

     “What’s a light?” asked Matthew.

     “A complete cycle of light and darkness,” replied the moon trog. “About eight human hours.”

     “One orbit of Kronos around Tharia,” said Thomas thoughtfully. “So they’ll keep us waiting here sixteen hours, will they?”

     “The Dallak is very busy,” replied the guardsman. “You’re lucky they agreed to see you at all. It’s very rare for humans to be allowed this deep inside our territory.”

     “They’re not going to be asking permission for much longer,” said Shaun. “Pretty soon they’re going to be coming whether you want them to or not.”

     The moon trog glared at him, and then the guardsmen turned and left.

     They weren’t locked in, for which they were grateful. They were allowed to wander at will around the cavern and explore the empty dwellings it contained, but they weren’t allowed through the airlock back out into the tunnel ‘in case you get lost’. The Tharians accepted this in good grace, since they knew that the moon trogs had to suspect them of being spies for the human city, and so they settled down in one of the empty dwellings, still in good condition despite its years of neglect.

     One of the keeper’s assistants showed them how to use the washing facilities, so that they could give themselves a good scrub and clean their filthy, bloodstained clothes, and they were given needles, cotton and a few scraps of cloth with which to repair the worst of the tears and holes. After a few hours they all looked reasonably presentable again. The soldiers still looked silly to the others wearing nothing but patched and sewn silken bathrobes, but that was the least of their worries at the moment.

     They then settled down to sleep. None of them were awake as the glowbottles faded to darkness two hours later, but they were woken up four hours after that by the sound of moon trogs adding just enough activating fluid to the darkened glowbottles to allow them to glow for another four hours, maintaining the cycle of four hours of light and four hours of darkness to which they’d become accustomed. Grumbling to each other, they settled back to continue their interrupted sleep, but after another couple of hours they were getting bored and looking for something to do to pass the time. The uncertainty, the not knowing what lay in store for them, made it impossible for them to relax, so that they felt nothing but great relief when the guardsmen finally came back for them.

     They were led down more tunnels and past more caverns until they came to a cavern larger than any of the others, a full two hundred and fifty yards long and a hundred yards wide, the entire inner surface of which was covered by elaborate and colourful gardens. The cavern also contained about a dozen large, impressive doorways surrounded by carvings and frescoes to make it clear to all visitors that they led not to private dwellings but to workplaces, the moon trog equivalent of public buildings. This is their town centre, thought Thomas, looking around in wonder. One of them, anyway. One of these doors leads through to the town hall, another to the library, another to the bank, if they use money. The opera and theatre or the local equivalents, all their public institutions. This is the very heart of moon trog society, he thought. The very centre of their territory.

     “No human has ever been here before,” said the leader of their escort. “I just thought you’d like to know that.”

     “We’re honoured,” replied Diana sincerely.

     The moon trog simply scowled at her and led them to the largest and most impressive of the doorways, beside which two moon trogs in different, more impressive uniforms were standing guard. "The Dallakhrim," said the leader of their escort in reply to Thomas’s question. "The Dallakarn's security force. They'll take you the rest of the way."

     There was a trace of something in his voice, however, a touch of bitterness and resentment, and the Dallakhrim showed a decidedly haughty manner as they dismissed the Tharians' escort.

     “So, even the moon trogs have class problems,” whispered Lirenna as the door opened and they were ushered in. “I’m not sure whether to be reassured or not.”

     The others grinned in agreement. All of Tharia’s civilized races were divided into various classes, with an upper, ruling class, a lower, working class and, usually, several specialised classes in between. It seemed to be a fundamental characteristic of all humanoid life everywhere. Even the shae folk weren't immune, with their reverence for old families whose forebears had been great poets, musicians or tenders of dwelling trees, even if the latest generations of those families failed to live up to the same standards. Many a shae had won an argument and convinced others upon a course of action because he was 'the grandson of Gildor the Harpist', rather than because of the merits of his ideas.

     When they entered the Dallakarn, a contingent of half a dozen Dallakhrim were waiting for them. They led them down a cylindrical corridor past rooms and other corridors above, below and on either side until they came to a room where they waited while a single moon trog went on ahead. Half an hour later he came back and the Tharians were led into the next room. The Dallak chamber itself.

     There were nine members of the Dallak, each one belted into a chair hanging three or four feet from the circular wall and about halfway between floor and ceiling. They formed a circle around the Tharians, who were led to the centre of the room where there was a framework of polished wooden poles for them to hold onto. This far from the surface of Kronos, the moon’s feeble gravity was reduced even further, and without something solid to hold onto they would have been floating helplessly all around the room. They saw that some of the wooden poles had leather straps attached to them, and they buckled them gratefully around their waists, allowing them to have their hands free and still be held securely in place.

     They looked curiously at the moon trogs around them. It was popularly believed that trogs wore nothing in the tunnels and caverns of their own cities, except when they were doing something that required protective clothing such as smithying and soldiering. Maybe that was true for Tharian trogs, but the Kronosian Dallak proved that the moon trogs, at least, believed in dressing for effect as well. Every member of the Dallak wore a loose, baggy but finely decorated jumpsuit that covered every inch of their bodies except their heads and their four hands, possibly to hide their grey, liverspotted skins, and they wore steel skullcaps that fitted closely above their eyes and ears, polished to a brilliant shine.

     They were also distinguished by the wearing of badges in the middle of their chests. The badges were octagonal, about eight inches across, and had designs in bright colours similar to the designs they’d seen painted on the shields of common Tharian trogs. Clan symbols, thought Thomas excitedly. They must still count themselves members of the clans from which their ancestors had originally come. He wondered how the common trogs would react if a bunch of moon trogs were to suddenly turn up claiming membership of their clan. Not that that was very likely. The moon trogs’ musculature had degenerated so much during their centuries in low gravity that they’d be virtually helpless on the surface of Tharia.

     Looking at the badges, he saw that they represented half a dozen different clans. The most common bore the design of two crossed scimitars, which he recognised but couldn’t put a name to. There were three of them, and the moon trogs wearing them were all sitting together and chatting to each other in their own language while pointedly ignoring their neighbours belonging to other clans. Thomas couldn’t help grinning. Some things never changed. On the other side of the room, however, a moon trog wearing the badge of the Longdrifts was chatting happily with another whose badge was that of the Black Alembic clan, and he remembered Angus telling him that, back on Tharia, those two clans had been at war for centuries. Probably best not to mention that, he thought.

     One of the moon trogs of the crossed scimitars clan then picked up a small metal hammer and tapped a gong with it, making a series of tinny high pitched chimes that silenced the rest of the room.

     “This extraordinary meeting of the Dallak is now in session,” he said in excellent common. “We have come here today on very short notice to hear the words of these visitors brought before us who claim to have come from Tharia, the fallen world. I need hardly spell out the implications for our race if this claim is true, and our task today and in the days ahead is to decide just how much credence we can place in it. If we decide that the threat is real, we must then decide what actions we can take to prepare ourselves for the momentous changes about to afflict our society.”

     The Tharians looked at each other nervously. This sounded as though it was going to be serious.