After a short distance they came to an intersection, the very same intersection at which Matthew had first come across the steel doors. This time Jerry operated the doors, just to make sure that he could do so despite his short stature and puny strength (he encountered only minor difficulties, much to his delight), and soon they were standing at the crossroads with steel doors all around them.
“That’s the way you went, isn’t it, Matt?” asked Shaun, indicating the doors that led further eastwards. Matthew confirmed that it was, so they went through the doors and continued on.
They found themselves back in a stretch of corridor with ordinary wooden doors on either side of them. This time they ignored them, though, since they were certain that they wouldn’t find the key there and were eager to reach the park cavern. Matthew stared at the door behind which the necklaces were, about thirty yards ahead of them, and strained his brain for an excuse to get them to go through it. This was a development he hadn’t counted on. He’d expected them to carry on searching every room they came to, in which case it would have been easy to ‘discover’ the necklaces, but now they were striding ahead with awful speed, devouring a full yard with every stride, and before he’d managed to come up with a single plausible excuse they’d reached the door and were passing it.
Not knowing what else to do, he stopped beside the door and struggled to find something sensible to say. “Er, er, I mean, er...”
“What is it, Matt?” asked Shaun, turning to look at him curiously. “Is anything wrong?”
“Well, er, I mean...” repeated Matthew, feeling his face going red with fear, shame and embarrassment, “Er, don’t you think we should be checking all these rooms? I mean, who knows what they might have in them? Don’t you think?”
“No need,” replied his brother confidently. “You checked them all when you came here before, didn’t you?”
“Well, er, not all of them,” said Matthew unhappily. “I don’t think I looked inside any of these. In fact the more I think about it, the more I think I didn’t.”
“Oh well, never mind,” replied Shaun indifferently. “I can’t be bothered to check any more rooms. I want to see this park cavern of yours. Come on.”
The young soldier looked even more unhappy. “It wouldn’t take a moment to just take a peek,” he pleaded, edging even closer to the door. “Come on, just one little look...”
“Matthew,” said Diana in her special tone of voice, “What are you up to?”
“Nothing! Nothing!” cried the young soldier in near terror. “I just thought, you know, that...”
“Matthew Winterwell!” said Diana sternly. “What are you playing at?” She opened the door and looked inside. “Well well,” she said in mock surprise. “Look what’s in here, another cabinet. What’s in it, Matt?”
“How should I...”
“Matthew!”
Matthew knew it was all over and broke down completely. The only thing he could do now was confess everything and throw himself at the mercy of the court. Numbly, he went over to the cabinet, opened it to the gasps of the others and produced the necklace he'd had hidden in his pocket. There was no need to say anything. His humiliation was complete and he hung his head in unbearable shame.
Shaun looked down at his feet to try to hide his face but his body was shaking and he raised a hand to wipe a tear from his eye. Diana's face remained stern but her lips narrowed with the effort. “You were wearing this when you went through the cavern?” she asked. Matthew nodded. “And you think it protected you from whatever killed everything else?”
Matthew nodded again. “I couldn’t let you go in without them,” he said wearily. “Just in case.”
“We’d all better take one, in that case,” said Shaun.
He took five more of the necklaces from the cabinet and passed them around. Soon, they were all wearing them, glittering in the light of the glowing marble globes, and Jerry looked around at his friends in delight. “My, don’t we all look pretty!” he laughed.
“Anything else you haven’t told us?” asked Shaun, still grinning.
“No, nothing else, I promise,” replied Matthew gloomily.
“Okay, let’s go then,” said Shaun, moving towards the door.
“Hey, wait a minute,” said Matthew in confusion. “Is that it? Aren’t you going to tell me off or anything?”
In reply, Diana put her arms around his neck and gave him a great big hug. Tried to, anyway. You can’t give anyone a proper hug when they’re wearing a slennhide breastplate, but she did her best. “Matthew, promise me something,” she said into his left ear. “Don’t ever change. Stay exactly the way you are, always.”
She then gave him a kiss on the cheek. The young soldier was so surprised that he was literally lost for words, and this time Shaun did burst into laughter, along with everyone else.
The moment soon passed, though, and Thomas went over to the splintery cabinet to see if he could find any clue as to what the necklaces did, assuming they weren’t just pieces of expensive jewelry. He saw the plaque on one of the doors, almost completely obscured by a crust of green oxide, and tried to rub it away with the sleeve of his robes. It was tough, but when Shaun saw what he was trying to do he came over to help, using the piece of sandpaper he normally used to clean the rust from the metal buckles and fixings of his uniform. Soon they’d removed enough of the encrustation to be able to make out the words underneath.
“Necklaces of Vacuum Breathing,” read Shaun curiously. “What’s vacuum?”
“Must be some kind of poison gas if you need magic necklaces to breath it,” replied Thomas. “It must be something they expected to come across quite often if they felt the need to make so many necklaces.”
“Maybe it seeps up from the centre of Kronos,” suggested Jerry. “You said there was a big crack in the park cavern, Matt?”
“Yeah,” confirmed Matthew, still giddy with relief at being let off the hook for his attempted larceny. “It went halfway across the ceiling, down the wall and partway across the floor. It was so wide I could see the stars through it, even though we’re so far underground.”
“Hmm,” said the tiny nome thoughtfully. “Suppose this vacuum stuff is constantly seeping up through pores in the rock. That’s not as crazy as it sounds. Back on Tharia, the trogs sometimes carry canaries around in their tunnels with them, because they’re much more sensitive to poison gas than we are, and if they fall off their perches the trogs clear out in a hurry. Anyway, normally the gas continues to go on up through the ceiling and up to the surface so that it never builds up to dangerous levels, but every so often it might seep up faster than normal so that it builds up faster than it can escape. Maybe it's the same here. Some kind of toxic moon gas. I would imagine that they would wear the necklaces while they found a way to let all the vacuum escape from the contaminated area. That must be what all these steel doors are for as well, they must be airtight. They make sure that if vacuum builds up in one area, it doesn’t spread all through the complex and kill everyone.”
“Yes!” agreed Thomas in delighted agreement. “And that’s why they’re in pairs as well. It’s so people can go through, one door at a time, while keeping the other door closed to prevent the vacuum from escaping. They’re like the locks on a canal that allow barges to go upstream. These steel doors are locks for air. Airlocks.”
“But that doesn’t explain what happened in the park cavern,” said Matthew. “Those people died suddenly and violently, not from some gradual buildup of gas.”
“Yes it does,” replied Jerry. “You said that that giant crack went down as well as up, so it would have allowed the gas to flow up from the centre of Kronos much faster than normal, reaching lethal levels in just a few minutes. I bet the crack in the floor came first and that the ceiling was intact at first, keeping the gas in. The ceiling only cracked open later, letting all the gas escape after everyone was already dead.”
“I don’t know,” said Matthew doubtfully. “It looked to me as though it was all one crack, and that the cavern just happened to get in its way.”
“Well, let’s go and see,” replied Shaun, and he led the way back out of the room.
Back in the corridor, they saw three more steel doors ahead of them whose twins, they knew, all had red flags in their windows and behind which was the cavern full of dead people. They approached it with trepidation, and it was with considerable nervousness that they went through the centre door and closed it behind them. Thomas looked nervously at the red flag in the other door’s window. “That must be what the flags mean,” he said. “They must mean that there’s vacuum on the other side.”
Jerry ran an admiring hand over the door. “This is a remarkable piece of work,” he said. “I don’t think there’s any magic in it at all, and yet it raises a little red flag to warn you there’s vacuum on the other side and only opens when the other door’s closed, so that you don’t accidentally contaminate the rest of the complex. It must all be done by mechanics and engineering. Those Agglemonians were clever chaps all right.”
“They may have had help from the clerics of Vulastos,” suggested Diana, also examining the door. “I saw some of their work once, and this has the same kind of look about it.”
“Who’s Vulastos?” asked Jerry. “I don’t think I’ve heard of him.”
“He’s the God of Mechanics and Engineering,” replied Diana. “He’s mainly worshipped by the trogs but he has a few human worshippers as well.”
“Enough chatter,” said Shaun impatiently, “Let’s get in there. Open the door, Matt.”
Matthew turned the smaller wheel on the door and soon the airlock was filled with the sound of rushing air passing through the small hole.
☆☆☆
Thomas dangled a small piece of cloth in front of the hole, and whistled in amazement as it was sucked through, almost literally snatched from his fingers. Air is passing through that door very quickly, he thought, but if the other door is airtight... He looked at the other door and ran a hand over it from top to bottom to see if any air was getting in that way, but there wasn’t. But that’s impossible! he thought in confusion. If you have air leaving with none coming in, then eventually... He began to suspect that they’d misunderstood what vacuum was, and as he pondered the matter further the first glimmerings of the true nature of vacuum began to occur to him.
He was so engrossed in his train of thought that he failed to notice the change in the airlock’s sound quality, and it wasn’t until he felt Lirenna’s hand shaking his shoulder that he realised that the sound of rushing air had stopped. Not only that, but all sounds had stopped, except those that originated inside his own body, and he realised for the first time that he could actually hear his own heart beating. He listened to it in fascination for several moments until he felt Lirenna shaking his shoulder again and realised that she was trying to tell him something. Her mouth was moving but no sounds were coming out. He saw that Matthew had opened the door, though, and, as the demi shae took his hand and gave it a gentle tug, he guessed that she was trying to tell him that they were going.
“Okay, I’m coming,” he said, and saw the look of puzzlement on her face as she tried to make out what he was saying. She can’t hear me either, he realised. This is weird.
Together they stepped out into the park cavern, and the young wizards stared in amazement. Thomas looked up at the ceiling, where he saw the giant fissure exactly as Matthew had described it, and he stared in fascination at the stars, shining down at them without the slightest trace of a twinkle. They disturbed him in a way he didn’t understand. Back home he enjoyed stargazing, but here, on Kronos, he had the very strong feeling that being able to see the stars was very bad. Very bad indeed. He wished he knew why.
He jumped in alarm when something touched his arm, but it was just Shaun trying to get his attention. Shaun had also been staring up at the stars, and there was a look on his face that almost looked like like fear. He was pointing back to the airlock from which they'd just emerged. His mouth was working as he tried to say something but Thomas heard only silence. It was clear to see what the soldier wanted, though, and so he followed the soldier back to the airlocks, followed by the others, and they went back through to the steel corridor.
"I had a thought while I was looking up at the stars," the soldier said as the others gathered around. "I thought it was important to share it with you."
"What?" asked Thomas, paying close attention. He sensed that this would be important.
"The stars reminded me of a time, a few years back, when a group of us from the village chased a group of bathkils that came down from the mountains. You remember, Matt?"
The younger brother nodded. "They'd attacked a number of homesteads," he told the wizards. "Killed the owners. Ate the children. We chased them back into the mountains and high up the slopes of Mt Rapid, the highest mountain for a hundred miles around, where we lost them."
"We had to give up half way up the mountain," Shaun continued. "We were all weak and gasping. Mountain sickness, they call it. No-one knows what causes it, but it only happens when you're high above the ground. I remember what the stars looked like up there, though." He pointed through the window in the airlock door, at the great fissure in the cavern's ceiling. "They looked like that. It's as if we're high up on a mountain instead of inside the smallest moon.
"I suppose, in a way, we are up on a mountain," said Thomas thoughtfully. "Kronos circles Tharia at an altitude of ten thousand miles, so it’s the same as being on top of a mountain ten thousand miles high. But if mountain sickness starts only half way up a normal mountain..."
"Master Mavwell, our geography teacher, was talking about that one day," said Lirenna, her brow furrowed as she tried to remember. "That you can't breathe the air when you're too high up. What was it he called it?"
"Thin air," said Thomas as he suddenly remembered. "He said the air becomes too thin when you're high up a mountain. That's what vacuum means. It's not some kind of poison gas. It means that the air's too thin to breathe."
"So what does thin mean?" asked Shaun. "What is it about air that makes it thick or thin?"
"He did say," Thomas admitted sheepishly, "but I was thinking about my potions practice at the time. I'd failed to create a successful Potion of Strength three times in a row and my potions master told me I'd better get it right the next time or I'd be in trouble. I wasn't really paying attention to some guy talking about thin air."
He looked at Jerry hopefully, but the tiny nome shook his head. "We went there to become wizards," he said. "We wanted to learn about magic. Who cares about mountain climbing?"
They both looked at Lirenna, who shook her head regretfully. Let's hope our failure to pay attention in class doesn't costs us our lives," she said.
The others nodded solemnly. "Was there anything else, Shaun?" asked Thomas.
"No," the soldier replied. "I just thought it was important to tell you about mountain fever. In case it was important."
"I think it was," the wizard replied. "Okay, then. Shall we go on?"
The others nodded, and so they went through the airlocks again, back into the cavern.
Very soon after that, they saw the first of the bodies. Diana knelt beside one of the mummified, mutilated corpses and tried to say a prayer over it, but discovered that she was also mute in the almost perfect vacuum. Undaunted, she squeezed her silver caroli flower and said a prayer in her mind for all the poor souls who’d died in this cavern, far too many for her to bless them all individually. Then she waved her hands to attract the attention of the others and gestured frantically towards the other side of the cavern. The others caught her meaning, as they were all thinking the same thing. Let’s get out of here. Let’s get out of this hideous place.
They walked on with a new burst of speed and soon came to the five airlocks where Matthew had seen the living Agglemonians. They waited while Shaun and Matthew gently removed the bodies that were packed inside the open airlock, carefully laying them out on the ground a few feet away, and then they all went in and closed the door behind them.
Matthew turned the small wheel opening the small hole in the second door, and soon they were able to speak again. “Okay then,” said Shaun, going up to the second door and grasping its wheel. “Are we ready to meet the survivors? If any of you has any doubts about this, now is the time to say so.”
“No, we’ve got to go in,” said Thomas. “They’ve got the key to the teleportation chamber. If we want to go home, we have to go in.”
“Agreed,” said Lirenna. “Open the door, Shaun.”
“Okay,” said the soldier, and he turned the wheel. He then pulled the door and it opened easily. He looked back at his friends one last time and then he led the way out of the airlock, into the outer, residential circle of the moon city.