“I think we’ve seen enough of Earth for a while,” Chrístõ said as his hands moved across the drive console. “And what you saw of Gallifrey was just like an English country estate. I think you should experience some really alien landscapes.”

Riley Davenport nodded his agreement. In truth, he didn’t have a lot of choice about the destinations the TARDIS brought him to. But he was quite happy to leave his fate in Chrístõ’s hands. He was nearly two hundred years old, after all. Riley yielded to his superior experience.

A soft trill emanated from beneath the console. Chrístõ grinned widely.

“Let’s find somewhere that Humphrey can enjoy as much as us,” he suggested. “I think I know the very place.”

The TARDIS materialised in a rocky, steep-walled canyon with a wide and swift flowing river running through it. With two suns beating down it looked anything but the place for a darkness creature who could be killed by direct sunlight. Humphrey was carefully hidden in a backpack that Riley volunteered to carry before he discovered how much mischief Chrístõ’s strange pet could make. The giggling noises were bad enough, but the backpack wobbled like a jelly every so often making it a very strange load to carry.

“He’s playing you up because you’ve never carried him before,” Chrístõ explained. He opened the zip a fraction and looked in. “Behave or we’ll leave you in the Cavern of the Suns.”

Humphrey trilled and settled down. A few minutes later a contented snoring started emanating from the pack.

“I mean it,” Chrístõ warned.

“He knows you’re lying,” Riley pointed out. “You’d never harm a living being deliberately, especially one as blameless as him.”

“I know. You have to behave, Humphrey. As well as tourists there are some very serious religious people who meditate in the caves. They’ll think you’re a demon or something and make a big fuss.”

Humphrey gave one big snore then settled down. Chrístõ grinned and turned his attention to the incredible landscape all around them. The gorge was a quarter mile wide with the sheer walls of rich blue cõpáld, one of the hardest substances in the universe, glittering in the sunlight. The high plateau of cõpáld had once been split apart by seismic forces exposing the river that flowed through the softer strata of poulstone and a network of caves and tunnels that were famous throughout the galaxy.

“Why are they famous?” Riley asked. “More famous than… I don’t know, Wookey Hole or the Blue John Caves in Derbyshire?

There was a shrill whistle from within the backpack. Chrístõ didn’t censure that one.

“Humphrey has friends in both of those places. Not sure about here. It would be interesting to find out. To answer your question, the Prathibtha Caves of Zostria V are famous for being among the biggest, deepest and most spectacular, and also for the religious rites that go on there every day. The whole complex is known as the Monastery in the Rocks.”

“That… sounds intriguing,” Riley managed to say.

“Very intriguing. Several of the caves are used by hermit monks for meditation. Others are used for group worship. The Cavern of the Suns is the most important of those. They have formal services five times a day in there. That one is not for Humphrey. He needs to be hunkered down in the dark when we go in there.”

“The people here… on this planet… the Zostrians… Are they Human?”

“Not in the sense of having originated on Sol Three in the Mutter Spiral – Earth to you. Their DNA is significantly different. Their blood is different to yours and they don’t have their internal organs in the same places, but they are humanoid in the sense of having one head, two arms and legs, hair and skin in the places you would expect them to be.”

“They… wouldn’t be… these religious rites… they’re not Christian rites?”

“No. They worship a god called Zost and their Holy Book is The Truth of Zost.”

“I was raised CofE. I was taught that there is only one God and, basically, one way to praise Him. Even Methodists were suspect. Catholics practically another species. The idea of taking part in the worship of an alien god is a bit….”

Chrístõ nodded in understanding.

“We’re not really going to be taking part, just standing at the back quietly. You won’t be asked to do anything against your personal beliefs.”

“That’s all right, then,” Riley decided and walking on in silence, aware of Humphrey deliberately wobbling about in the backpack.

After a quarter mile or so, the gorge closed in as they walked and the river was louder and faster, the sound concentrated by the high walls.

When the gorge was no more than fifty metres across, the river filling most of the level ground apart from a path just wide enough for the two visitors to walk side by side, they passed under a landbridge created by a narrow spur of cõpáld. A tree clung to the sparse topsoil, its roots bare and white in the empty air. Fifty paces on was a wider ‘bridge’, again covered in the sort of vegetation that spread across the top of the gorge on either side. Again they emerged into sunlight, but only for a short while. Now it was more like they were entering a tunnel with wide holes in the roof.

“Amazing to think that something like that blue rock that made up the walls of the gorge could be as thin and fragile as it is up there above us,” Riley commented.

“Even cõpáld can be weathered and shaped by erosion,” Chrístõ replied. “Once seismic forces cause cracks to form, even diamond is vulnerable, let alone cõpáld.”

Riley looked up again, nervously.

“It’s not going to fall while you’re passing under it,” Chrístõ assured him.

These ‘bridges’ of cõpáld were only the preview to the main show. Before they were cut off completely from the natural light they reached the entrance to the famous Prathibtha Caves. Riley had expected to have to duck as he passed into the cave, but the entrance was bigger than Victoria station. Four locomotives side by side could have parked there and three stacked on top of each other would still be short of the roof.

They were both a little surprised to see a fence with a toll booth and a turnstile blocking the way some fifty paces from the sheer cliff face of deep blue cõpáld. A small crowd were passing through the barrier one at a time. They were a mixed group of biped humanoids who very definitely didn’t originate on Earth. Chrístõ recognised the ochre-red skinned Zocci and eucalyptus-green Vinvocci as well as chalk white, stick-thin, seven-foot

tall Meringians and two ebony giants from Epploxia who were even taller with broad shoulders and stout limbs.

“University of Cassiopeia,” Chrístõ noted. “They accept every sentient life form. On their own worlds, Zocci and Vinvocci hate each other, but at the University they have to work together.”

“They’re visiting the caves.”

“Famous throughout the galaxy.”

Riley was going to say something else but his eyes caught a movement high up on the cliff. A group of young Zostrians, distinguished from the visitors by their short stature and round faces stood on an outcrop directly above the huge cave entrance. Suddenly one of them leaped head first off the ledge. Riley gasped in shock before he realised that the man had a long elastic rope attached to his legs. He swung at the end of it several times before his friends reeled him in.

“It’s called the ‘Trial of Zost’,” Chrístõ explained. “A proof of faith. It’s not compulsory for visitors, only Zostrians preparing for Confirmation.”

“Glad to hear it,” Riley answered. “Confirmation is a bit easier in the CofE.”

Chrístõ smiled and refrained from explaining that such activity was called ‘bungee-jumping’ on Earth at the latter end of Riley’s century and didn’t require religious faith, only in the person tying the rope.

The university group passed through the turnstile. Chrístõ and Riley moved up to discover that the booth was unmanned. Maps and timetables for the religious services were free to take. There was no formal charge for entry, but a touch screen allowed visitors to make donations from three hundred different currencies and five hundred types of credit card. Chrístõ made a generous donation. He hadn’t used much of his allowance during his visits to parts of ancient Earth and he could afford generosity. He and Riley passed through the turnstile and headed towards the cavernous entrance to the famous Prathibtha Caves.

It was a beautiful introduction to the cave system. High above their heads, higher than the ceiling of any cathedral, railway station or even the Albert Hall, a million glittering stalactites infused with a natural phosphorescence caused by the chemical reaction of rain water and dissolved poulstone lit the cavern with a soft blue-green glow.

“It’s like being underwater,” Chrístõ remarked as he unzipped the backpack and let Humphrey tumble out excitedly. “Keep close to us and no scaring the tourists,” he ordered. Humphrey responded with a trill that might have had a hint of defiance in it, but he basked in the harmless aquatic glow as he bowled along ‘at heel’ like a well-trained dog.

At the far end of the entrance cave were two options. The voices of the university crowd echoed in a wide, tall passage reminiscent of the processional entrance to Westminster Abbey. To the left of it was a tunnel that a tall man could just stand upright in.

Chrístõ consulted the map.

“These are the ?????? ????? and the ????? ?????. Depending on your translation programme that’s either big entrance and small entrance or big hole and small hole. Both sound like potential innuendos, so let’s not dwell on them for too long. I suggest….”

But Humphrey made the decision for them, rolling into the small hole.

“He’s probably right,” Riley considered. “I don’t know if I want to be trailing after the students all day. Besides – ‘I took the one less travelled by….’”

“And that has made all the difference.” Chrístõ smiled as he supplied the last line of Robert Frost’s most famous poem. “I’ve lived by that axiom ever since I set out into the universe on my first field trip. Humphrey’s choice it is.”

The blue-green glow was fainter in the passage but enough to see by. Humphrey bowled ahead as Chrístõ and Riley both inclined their heads enough to walk without fear of banging them on the ceiling. At intervals they paused to look at primitive drawings that had been painted with inky clay some half a million years ago. They depicted a hunter-gatherer society that hunkered down in the caves for the winter and developed the earliest religious devotion, praying for the return of warmth and abundant food, the necessities of primitive life.

“What’s that?” Riley asked, pointing to a misshapen giant in one image.

“Something they hunted?” Chrístõ guessed. “Like a mammoth on Earth?”

“It doesn’t quite look like a hunting party,” Riley mused. Chrístõ agreed. The primitive figures seemed to be bowing before the strange, amorphous creature. But it was difficult to read anything into such basic images. They left the mystery and moved on, the

tunnel inclining downwards gently but insistently until Chrístõ estimated that they were a good quarter of a mile below the level where they entered the tunnel.

“You can do that sort of maths in your head?” Riley asked. “That’s distance times gradient isn’t it?”

“I can feel it,” Chrístõ answered. “It’s not a regular Time Lord talent. I think it’s because there are gold mines on our family estate. Not that any of my family ever did any such a manual job as gold mining, but we seem to have an instinct for being underground.”

“I just feel tired,” Riley commented. “Funny that, it’s not THAT steep and I’ve walked more than a quarter mile downhill before.”

“The air is fine,” Chrístõ noted. “Yes, I can detect the constituents of air. Maybe you need a quick energy burst. Hold on.”

He shrugged off his own backpack and fished in the side pocket for two foil wrapped disks.

“Kendal mint cake,” he said. “One of the many things your world does well. Better tasting than the energy bars sold in space ports, bigger sugar rush for tired explorers.”

Riley accepted the snack gratefully as they continued on past increasingly detailed images in which the blobby giant featured often. Chrístõ felt that he ought to study them more closely, but there was so much more he wanted to see and if Riley was already tired they would barely get through it all.

The tunnel’s gradient flattened out and they reached the first of the contemplation caves. The two visitors, with Humphrey keeping close by, walked on a special surface that softened footsteps as they passed through a cave with a floor broken up by thick stalagmites reaching up to meet their stalactites counterparts. Here and there a thick pillar was formed by the meeting of the two. Pools of clear, still water reflected the blue-green ceiling.

Between the stalagmites, sitting nearly as still, were men in russet-red cowled cloaks. They were the Zost worshipping monks who came to mediate here, deep underground, away from any distractions. There were twenty of them here, each locked in intense trances from which the footsteps of visitors would not have been a disturbance. The softening of the sound was merely a courtesy to them.

Neither of the visitors spoke as they passed through the cave. Even Humphrey was quiet. When they passed through a natural portal into another passage both breathed out. They had almost forgotten to breathe in the still atmosphere of that cave.

“Those monks are incredible,” Riley said. “They don’t even look like they’re breathing.”

“If they’ve reached a sufficient level of trance they probably aren’t taking more than a breath a minute,” Chrístõ explained. “Heart rate will be slowed right down. They won’t need more than that.”

“Incredible.”

“I can slow my breathing down to one breath an hour,’ Chrístõ added. “But that’s a specific Time Lord trick. Most other species can’t go that deep.”

“I wouldn’t know where to start.”

“I could show you. It is very good for the soul to purge it of all worries and complications for a while.”

“Some other time,” Riley said vaguely. “Is Humphrey all right? He seems… quiet.”

Humphrey was not quiet. He was emitting a very low sound, almost too low to hear. Chrístõ concentrated on it and was filled with a seen of foreboding.

“What is it, old boy?” he asked. Humphrey trilled sadly but wasn’t able to explain his mood. “I don’t know. Perhaps he’s disappointed there aren’t any of his kind around these caves. But we knew it was a long shot. This planet is right on the outer edge of the Milky Way, millions of light years from where you were born, old boy, even further to Earth where we found the other colony of your kind.”

“I don’t think he’s SAD,” Riley pointed out. “I think he’s tired, like me.”

“I have never heard of him being tired before. I didn’t think his body used energy the same way. Perhaps he’s empathising with you.”

That seemed like a reasonable explanation, though Chrístõ wasn’t completely satisfied with it – despite it being his own suggestion. He couldn’t understand, either, why Riley was so tired. The air was good. They were not tackling any serious gradients. The had

climbed the Hanging Gardens, the Pharos Lighthouse, the Mausoleum, with no more than pauses to catch a breath.

Perhaps Riley was coming down with flu or something? When they got back to the TARDIS a quick medical scan might be in order.

Meanwhile they tried to enjoy the beautiful caverns and caves with magnificent examples of natural karst formations – a giant blue-green luminous ‘pipe organ’ formed on the wall of one cavern, the natural sculpture reflected in a crystal clear lake. The Forest Cavern was so densely packed with floor to ceiling pillars where stalagmites and stalactites had joined that it really resembled a petrified forest.

Riley tried to enjoy all of the wondrous sights, but his weariness was more and more of a hindrance to him the further they walked.

“I think we should call it a day,” Chrístõ decided. “I should take you back to the TARDIS.” He consulted the map. “The quickest way out, now, is up through the Cavern of the Suns. There is a service on, but we’ll go quietly and try not to disturb anyone.”

“Quietly is the only way I CAN go at the moment,” Riley answered with a last vestige of energy. He stumbled along behind Chrístõ, Humphrey at his heels in a desultory way. The gentle incline towards the upper level Cavern of the Suns exhausted him. Chrístõ dropped back and supported him.

“Not far, now,” he said. “Just through the Cavern, then a short way to the large entrance.”

“To tired even for innuendo,” Riley murmured.

When they reached the Cavern of the Suns, though, they were both shocked. The massive cavern was famous for two huge holes in the roof that looked like huge eyes framing parts of the Zostrian sky and, at present, a fraction of one of the planet’s five moons. Five times during each day, the precise moment carefully worked out by Zostrian astronomers, one of the suns aligned with either the left or right eye, filling the cavern with warm, bright light. The services of devotion to Zost were timed so that the explosion of light came at the climax of the ceremony, filling the worshippers with a sense of the miraculous.

But something was wrong. The cavern was not filled with voices intoning the Word of Zost. Instead, there was an eerie silence. The worshippers, including the multi-raced group of university students, were all slumped on the floor.

Chrístõ left Riley leaning against the wall and examined one of the Zostrian believers as well as the visitors who had very different metabolisms. All were in deep REM sleep, and they couldn’t be woken up by any ordinary means.

He decided not to try. Instead he brought Riley and let him lie down with them. He opened the backpack and invited Humphrey to crawl back inside.

“You’re safer in there,” he told his strange friend. “You stay there with everyone else. Don’t snore too loud. This is still a place of worship and snoring is rude.”

Humphrey trilled weakly as Chrístõ zipped him up safely. Riley was already asleep. He reluctantly left his friends and the other victims of something he was sure was nothing natural to this place.

He had one clue. He consulted the map and found a narrow passage, not normally used by the tourists, that intersected with the small entrance tunnel. He was thankful for the blue-green glow as he ran over an uneven surface that hadn’t been worn smooth by regular footfall. He was bent almost double at one point, but he came through at last to the tunnel he and Riley had walked along – the one with the interesting primitive drawings.

He studied them carefully this time, and a lot of his questions were answered. For the rest he needed more than a map of the caves.

He ran downhill, towards the Caves of Contemplation. He found the big one where twenty of the monks silently knelt among the karst formations. He chose a young monk who hadn’t yet grown a long beard through such intense devotions. He knelt opposite him, like a reflection. He let his own mind slip into a deep trance, but one where he, metaphorically, at least, kept one eye on the waking world.

He reached out to the young monk. He found his name and called to him.

“Kayle,” he called out with his mind. “I looked at the pictures. Long, long ago a monster lived in these caves, didn’t it?”

“The Thesperus,” Kayle replied. “The primitive people worshipped it. Before we knew the love of Zost. The Thesperus took part of their souls as part of their devotions. Not

much, but a little each day. But… it got greedy. It took more. They were courageous. They fought the false god and imprisoned it deep beneath the caves of devotion, where it could not reach them. It starved and withered.”

“Yes, I read that, too,” Chrístõ said. “But I don’t think it’s dead. While it was just generations of your lot meditating, it wasn’t able to do much… just a fraction of your lifeforce – your physical energy, not your soul. Nothing can take any sentient being’s soul except his own dark deeds. It took energy. But over time, it grew stronger. The popularity of the caves with secular visitors allowed it to take more and more. Now it really is greedy and it is hurting people. My Human friend and a lot of other people are being used by the Thesperus and I have to stop it.”

“We hold it back with our meditations,” Kayle said. “But you are right, it has grown stronger.”

“It never occurred go anyone to close the caves to visitors?”

“I regret the elders of our Brotherhood did not do that.”

“Never mind. Do you know how to get to the place where the Thesperus was incarcerated?”

“I think so.” Chrístõ felt an image of the tourist map with another of those unused passages marked. “But the way is blocked. It has been blocked since before we knew the love of Zost.”

“When the time is right, you and your fellow Brothers concentrate your meditations. You’ll know when and where. You can do your bit to make this right.”

He gently withdrew from the psychic connection and opened his eyes. Kayle did not move. Chrístõ quietly but quickly left the Cave of Devotions. He closed his eyes and consulted the mental map now lodged in his mind and turned the right way.

It was darker now as he descended through very tight, low passages. There had been far less karst formation here, below the level of the underground river and the cave lakes. Only small amounts of the blue-green glow kept the passages from being pitch black. Chrístõ hurried, disregarding his own safety. A few bumped heads and skinned elbows didn’t matterThe Prathibtha Caves

“I think we’ve seen enough of Earth for a while,” Chrístõ said as his hands moved across the drive console. “And what you saw of Gallifrey was just like an English country estate. I think you should experience some really alien landscapes.”

Riley Davenport nodded his agreement. In truth, he didn’t have a lot of choice about the destinations the TARDIS brought him to. But he was quite happy to leave his fate in Chrístõ’s hands. He was nearly two hundred years old, after all. Riley yielded to his superior experience.

A soft trill emanated from beneath the console. Chrístõ grinned widely.

“Let’s find somewhere that Humphrey can enjoy as much as us,” he suggested. “I think I know the very place.”

The TARDIS materialised in a rocky, steep-walled canyon with a wide and swift flowing river running through it. With two suns beating down it looked anything but the place for a darkness creature who could be killed by direct sunlight. Humphrey was carefully hidden in a backpack that Riley volunteered to carry before he discovered how much mischief Chrístõ’s strange pet could make. The giggling noises were bad enough, but the backpack wobbled like a jelly every so often making it a very strange load to carry.

“He’s playing you up because you’ve never carried him before,” Chrístõ explained. He opened the zip a fraction and looked in. “Behave or we’ll leave you in the Cavern of the Suns.”

Humphrey trilled and settled down. A few minutes later a contented snoring started emanating from the pack.

“I mean it,” Chrístõ warned.

“He knows you’re lying,” Riley pointed out. “You’d never harm a living being deliberately, especially one as blameless as him.”

“I know. You have to behave, Humphrey. As well as tourists there are some very serious religious people who meditate in the caves. They’ll think you’re a demon or something and make a big fuss.”

Humphrey gave one big snore then settled down. Chrístõ grinned and turned his attention to the incredible landscape all around them. The gorge was a quarter mile wide with the sheer walls of rich blue cõpáld, one of the hardest substances in the universe, glittering in the sunlight. The high plateau of cõpáld had once been split apart by seismic forces exposing the river that flowed through the softer strata of poulstone and a network of caves and tunnels that were famous throughout the galaxy.

“Why are they famous?” Riley asked. “More famous than… I don’t know, Wookey Hole or the Blue John Caves in Derbyshire?

There was a shrill whistle from within the backpack. Chrístõ didn’t censure that one.

“Humphrey has friends in both of those places. Not sure about here. It would be interesting to find out. To answer your question, the Prathibtha Caves of Zostria V are famous for being among the biggest, deepest and most spectacular, and also for the religious rites that go on there every day. The whole complex is known as the Monastery in the Rocks.”

“That… sounds intriguing,” Riley managed to say.

“Very intriguing. Several of the caves are used by hermit monks for meditation. Others are used for group worship. The Cavern of the Suns is the most important of those. They have formal services five times a day in there. That one is not for Humphrey. He needs to be hunkered down in the dark when we go in there.”

“The people here… on this planet… the Zostrians… Are they Human?”

“Not in the sense of having originated on Sol Three in the Mutter Spiral – Earth to you. Their DNA is significantly different. Their blood is different to yours and they don’t have their internal organs in the same places, but they are humanoid in the sense of having one head, two arms and legs, hair and skin in the places you would expect them to be.”

“They… wouldn’t be… these religious rites… they’re not Christian rites?”

“No. They worship a god called Zost and their Holy Book is The Truth of Zost.”

“I was raised CofE. I was taught that there is only one God and, basically, one way to praise Him. Even Methodists were suspect. Catholics practically another species. The idea of taking part in the worship of an alien god is a bit….”

Chrístõ nodded in understanding.

“We’re not really going to be taking part, just standing at the back quietly. You won’t be asked to do anything against your personal beliefs.”

“That’s all right, then,” Riley decided and walking on in silence, aware of Humphrey deliberately wobbling about in the backpack.

After a quarter mile or so, the gorge closed in as they walked and the river was louder and faster, the sound concentrated by the high walls.

When the gorge was no more than fifty metres across, the river filling most of the level ground apart from a path just wide enough for the two visitors to walk side by side, they passed under a landbridge created by a narrow spur of cõpáld. A tree clung to the sparse topsoil, its roots bare and white in the empty air. Fifty paces on was a wider ‘bridge’, again covered in the sort of vegetation that spread across the top of the gorge on either side. Again they emerged into sunlight, but only for a short while. Now it was more like they were entering a tunnel with wide holes in the roof.

“Amazing to think that something like that blue rock that made up the walls of the gorge could be as thin and fragile as it is up there above us,” Riley commented.

“Even cõpáld can be weathered and shaped by erosion,” Chrístõ replied. “Once seismic forces cause cracks to form, even diamond is vulnerable, let alone cõpáld.”

Riley looked up again, nervously.

“It’s not going to fall while you’re passing under it,” Chrístõ assured him.

These ‘bridges’ of cõpáld were only the preview to the main show. Before they were cut off completely from the natural light they reached the entrance to the famous Prathibtha Caves. Riley had expected to have to duck as he passed into the cave, but the entrance was bigger than Victoria station. Four locomotives side by side could have parked there and three stacked on top of each other would still be short of the roof.

They were both a little surprised to see a fence with a toll booth and a turnstile blocking the way some fifty paces from the sheer cliff face of deep blue cõpáld. A small crowd were passing through the barrier one at a time. They were a mixed group of biped humanoids who very definitely didn’t originate on Earth. Chrístõ recognised the ochre-red skinned Zocci and eucalyptus-green Vinvocci as well as chalk white, stick-thin, seven-foot

tall Meringians and two ebony giants from Epploxia who were even taller with broad shoulders and stout limbs.

“University of Cassiopeia,” Chrístõ noted. “They accept every sentient life form. On their own worlds, Zocci and Vinvocci hate each other, but at the University they have to work together.”

“They’re visiting the caves.”

“Famous throughout the galaxy.”

Riley was going to say something else but his eyes caught a movement high up on the cliff. A group of young Zostrians, distinguished from the visitors by their short stature and round faces stood on an outcrop directly above the huge cave entrance. Suddenly one of them leaped head first off the ledge. Riley gasped in shock before he realised that the man had a long elastic rope attached to his legs. He swung at the end of it several times before his friends reeled him in.

“It’s called the ‘Trial of Zost’,” Chrístõ explained. “A proof of faith. It’s not compulsory for visitors, only Zostrians preparing for Confirmation.”

“Glad to hear it,” Riley answered. “Confirmation is a bit easier in the CofE.”

Chrístõ smiled and refrained from explaining that such activity was called ‘bungee-jumping’ on Earth at the latter end of Riley’s century and didn’t require religious faith, only in the person tying the rope.

The university group passed through the turnstile. Chrístõ and Riley moved up to discover that the booth was unmanned. Maps and timetables for the religious services were free to take. There was no formal charge for entry, but a touch screen allowed visitors to make donations from three hundred different currencies and five hundred types of credit card. Chrístõ made a generous donation. He hadn’t used much of his allowance during his visits to parts of ancient Earth and he could afford generosity. He and Riley passed through the turnstile and headed towards the cavernous entrance to the famous Prathibtha Caves.

It was a beautiful introduction to the cave system. High above their heads, higher than the ceiling of any cathedral, railway station or even the Albert Hall, a million glittering stalactites infused with a natural phosphorescence caused by the chemical reaction of rain water and dissolved poulstone lit the cavern with a soft blue-green glow.

“It’s like being underwater,” Chrístõ remarked as he unzipped the backpack and let Humphrey tumble out excitedly. “Keep close to us and no scaring the tourists,” he ordered. Humphrey responded with a trill that might have had a hint of defiance in it, but he basked in the harmless aquatic glow as he bowled along ‘at heel’ like a well-trained dog.

At the far end of the entrance cave were two options. The voices of the university crowd echoed in a wide, tall passage reminiscent of the processional entrance to Westminster Abbey. To the left of it was a tunnel that a tall man could just stand upright in.

Chrístõ consulted the map.

“These are the ?????? ????? and the ????? ?????. Depending on your translation programme that’s either big entrance and small entrance or big hole and small hole. Both sound like potential innuendos, so let’s not dwell on them for too long. I suggest….”

But Humphrey made the decision for them, rolling into the small hole.

“He’s probably right,” Riley considered. “I don’t know if I want to be trailing after the students all day. Besides – ‘I took the one less travelled by….’”

“And that has made all the difference.” Chrístõ smiled as he supplied the last line of Robert Frost’s most famous poem. “I’ve lived by that axiom ever since I set out into the universe on my first field trip. Humphrey’s choice it is.”

The blue-green glow was fainter in the passage but enough to see by. Humphrey bowled ahead as Chrístõ and Riley both inclined their heads enough to walk without fear of banging them on the ceiling. At intervals they paused to look at primitive drawings that had been painted with inky clay some half a million years ago. They depicted a hunter-gatherer society that hunkered down in the caves for the winter and developed the earliest religious devotion, praying for the return of warmth and abundant food, the necessities of primitive life.

“What’s that?” Riley asked, pointing to a misshapen giant in one image.

“Something they hunted?” Chrístõ guessed. “Like a mammoth on Earth?”

“It doesn’t quite look like a hunting party,” Riley mused. Chrístõ agreed. The primitive figures seemed to be bowing before the strange, amorphous creature. But it was difficult to read anything into such basic images. They left the mystery and moved on, the

tunnel inclining downwards gently but insistently until Chrístõ estimated that they were a good quarter of a mile below the level where they entered the tunnel.

“You can do that sort of maths in your head?” Riley asked. “That’s distance times gradient isn’t it?”

“I can feel it,” Chrístõ answered. “It’s not a regular Time Lord talent. I think it’s because there are gold mines on our family estate. Not that any of my family ever did any such a manual job as gold mining, but we seem to have an instinct for being underground.”

“I just feel tired,” Riley commented. “Funny that, it’s not THAT steep and I’ve walked more than a quarter mile downhill before.”

“The air is fine,” Chrístõ noted. “Yes, I can detect the constituents of air. Maybe you need a quick energy burst. Hold on.”

He shrugged off his own backpack and fished in the side pocket for two foil wrapped disks.

“Kendal mint cake,” he said. “One of the many things your world does well. Better tasting than the energy bars sold in space ports, bigger sugar rush for tired explorers.”

Riley accepted the snack gratefully as they continued on past increasingly detailed images in which the blobby giant featured often. Chrístõ felt that he ought to study them more closely, but there was so much more he wanted to see and if Riley was already tired they would barely get through it all.

The tunnel’s gradient flattened out and they reached the first of the contemplation caves. The two visitors, with Humphrey keeping close by, walked on a special surface that softened footsteps as they passed through a cave with a floor broken up by thick stalagmites reaching up to meet their stalactites counterparts. Here and there a thick pillar was formed by the meeting of the two. Pools of clear, still water reflected the blue-green ceiling.

Between the stalagmites, sitting nearly as still, were men in russet-red cowled cloaks. They were the Zost worshipping monks who came to mediate here, deep underground, away from any distractions. There were twenty of them here, each locked in intense trances from which the footsteps of visitors would not have been a disturbance. The softening of the sound was merely a courtesy to them.

Neither of the visitors spoke as they passed through the cave. Even Humphrey was quiet. When they passed through a natural portal into another passage both breathed out. They had almost forgotten to breathe in the still atmosphere of that cave.

“Those monks are incredible,” Riley said. “They don’t even look like they’re breathing.”

“If they’ve reached a sufficient level of trance they probably aren’t taking more than a breath a minute,” Chrístõ explained. “Heart rate will be slowed right down. They won’t need more than that.”

“Incredible.”

“I can slow my breathing down to one breath an hour,’ Chrístõ added. “But that’s a specific Time Lord trick. Most other species can’t go that deep.”

“I wouldn’t know where to start.”

“I could show you. It is very good for the soul to purge it of all worries and complications for a while.”

“Some other time,” Riley said vaguely. “Is Humphrey all right? He seems… quiet.”

Humphrey was not quiet. He was emitting a very low sound, almost too low to hear. Chrístõ concentrated on it and was filled with a seen of foreboding.

“What is it, old boy?” he asked. Humphrey trilled sadly but wasn’t able to explain his mood. “I don’t know. Perhaps he’s disappointed there aren’t any of his kind around these caves. But we knew it was a long shot. This planet is right on the outer edge of the Milky Way, millions of light years from where you were born, old boy, even further to Earth where we found the other colony of your kind.”

“I don’t think he’s SAD,” Riley pointed out. “I think he’s tired, like me.”

“I have never heard of him being tired before. I didn’t think his body used energy the same way. Perhaps he’s empathising with you.”

That seemed like a reasonable explanation, though Chrístõ wasn’t completely satisfied with it – despite it being his own suggestion. He couldn’t understand, either, why Riley was so tired. The air was good. They were not tackling any serious gradients. The had

climbed the Hanging Gardens, the Pharos Lighthouse, the Mausoleum, with no more than pauses to catch a breath.

Perhaps Riley was coming down with flu or something? When they got back to the TARDIS a quick medical scan might be in order.

Meanwhile they tried to enjoy the beautiful caverns and caves with magnificent examples of natural karst formations – a giant blue-green luminous ‘pipe organ’ formed on the wall of one cavern, the natural sculpture reflected in a crystal clear lake. The Forest Cavern was so densely packed with floor to ceiling pillars where stalagmites and stalactites had joined that it really resembled a petrified forest.

Riley tried to enjoy all of the wondrous sights, but his weariness was more and more of a hindrance to him the further they walked.

“I think we should call it a day,” Chrístõ decided. “I should take you back to the TARDIS.” He consulted the map. “The quickest way out, now, is up through the Cavern of the Suns. There is a service on, but we’ll go quietly and try not to disturb anyone.”

“Quietly is the only way I CAN go at the moment,” Riley answered with a last vestige of energy. He stumbled along behind Chrístõ, Humphrey at his heels in a desultory way. The gentle incline towards the upper level Cavern of the Suns exhausted him. Chrístõ dropped back and supported him.

“Not far, now,” he said. “Just through the Cavern, then a short way to the large entrance.”

“To tired even for innuendo,” Riley murmured.

When they reached the Cavern of the Suns, though, they were both shocked. The massive cavern was famous for two huge holes in the roof that looked like huge eyes framing parts of the Zostrian sky and, at present, a fraction of one of the planet’s five moons. Five times during each day, the precise moment carefully worked out by Zostrian astronomers, one of the suns aligned with either the left or right eye, filling the cavern with warm, bright light. The services of devotion to Zost were timed so that the explosion of light came at the climax of the ceremony, filling the worshippers with a sense of the miraculous.

But something was wrong. The cavern was not filled with voices intoning the Word of Zost. Instead, there was an eerie silence. The worshippers, including the multi-raced group of university students, were all slumped on the floor.

Chrístõ left Riley leaning against the wall and examined one of the Zostrian believers as well as the visitors who had very different metabolisms. All were in deep REM sleep, and they couldn’t be woken up by any ordinary means.

He decided not to try. Instead he brought Riley and let him lie down with them. He opened the backpack and invited Humphrey to crawl back inside.

“You’re safer in there,” he told his strange friend. “You stay there with everyone else. Don’t snore too loud. This is still a place of worship and snoring is rude.”

Humphrey trilled weakly as Chrístõ zipped him up safely. Riley was already asleep. He reluctantly left his friends and the other victims of something he was sure was nothing natural to this place.

He had one clue. He consulted the map and found a narrow passage, not normally used by the tourists, that intersected with the small entrance tunnel. He was thankful for the blue-green glow as he ran over an uneven surface that hadn’t been worn smooth by regular footfall. He was bent almost double at one point, but he came through at last to the tunnel he and Riley had walked along – the one with the interesting primitive drawings.

He studied them carefully this time, and a lot of his questions were answered. For the rest he needed more than a map of the caves.

He ran downhill, towards the Caves of Contemplation. He found the big one where twenty of the monks silently knelt among the karst formations. He chose a young monk who hadn’t yet grown a long beard through such intense devotions. He knelt opposite him, like a reflection. He let his own mind slip into a deep trance, but one where he, metaphorically, at least, kept one eye on the waking world.

He reached out to the young monk. He found his name and called to him.

“Kayle,” he called out with his mind. “I looked at the pictures. Long, long ago a monster lived in these caves, didn’t it?”

“The Thesperus,” Kayle replied. “The primitive people worshipped it. Before we knew the love of Zost. The Thesperus took part of their souls as part of their devotions. Not

much, but a little each day. But… it got greedy. It took more. They were courageous. They fought the false god and imprisoned it deep beneath the caves of devotion, where it could not reach them. It starved and withered.”

“Yes, I read that, too,” Chrístõ said. “But I don’t think it’s dead. While it was just generations of your lot meditating, it wasn’t able to do much… just a fraction of your lifeforce – your physical energy, not your soul. Nothing can take any sentient being’s soul except his own dark deeds. It took energy. But over time, it grew stronger. The popularity of the caves with secular visitors allowed it to take more and more. Now it really is greedy and it is hurting people. My Human friend and a lot of other people are being used by the Thesperus and I have to stop it.”

“We hold it back with our meditations,” Kayle said. “But you are right, it has grown stronger.”

“It never occurred go anyone to close the caves to visitors?”

“I regret the elders of our Brotherhood did not do that.”

“Never mind. Do you know how to get to the place where the Thesperus was incarcerated?”

“I think so.” Chrístõ felt an image of the tourist map with another of those unused passages marked. “But the way is blocked. It has been blocked since before we knew the love of Zost.”

“When the time is right, you and your fellow Brothers concentrate your meditations. You’ll know when and where. You can do your bit to make this right.”

He gently withdrew from the psychic connection and opened his eyes. Kayle did not move. Chrístõ quietly but quickly left the Cave of Devotions. He closed his eyes and consulted the mental map now lodged in his mind and turned the right way.

It was darker now as he descended through very tight, low passages. There had been far less karst formation here, below the level of the underground river and the cave lakes. Only small amounts of the blue-green glow kept the passages from being pitch black. Chrístõ hurried, disregarding his own safety. A few bumped heads and skinned elbows didn’t matterwhen his friends and dozens of innocent civilians were at risk.

As predicted, the tunnel ended in a blockage. The rocks that fell did so a very long time ago and the mixture of soft poulstone and hard cõpáld was a very solid mass.

But he was a Time Lord. Millennia were nothing to him.

Well, in truth, they were. This was going to take a lot of effort. When he first learnt to excite rock with the power of his mind, he had fainted. He only avoided the derision of his classmates because four other ‘pure-blooded’ Time Lord candidates took even longer to recover than he did.

But that lesson had involved solid pieces of granite. This was an amalgam. Reminding it that it had once been separate pieces of rock was probably easier.

Probably….

It was still hard work. His mind hurt as he concentrated all of his will on the ten feet of densely packed debris.

But slowly it began to happen. The wall crumbled, a few grains at first, but then a torrent of loose pebbles and dust. He stepped back and watched the wall collapse leaving a dark void behind.

A dark void from which a ferocious roar came along with the stale smell of air that had been trapped for millennia. Then he saw movement. Again he took an instinctive step backwards. He knew what the creature – the Thesperus – would look like and he wasn’t entirely looking forward to a close encounter.

It was mud coloured, thick, rippling flesh like a manatee but four time the size and shuffling forward on its stomach. The sound of its body moving over the loose gravel was indescribably horrible.

“This is when I need you all,” Chrístõ said with his mind. He felt the answer from Kayle and his friends as a gestalt voice. Then he felt them join with him. Together they focussed their minds on the creature. They blocked it from taking any more energy from the victims above, then they turned their minds on it. They found its central nervous system and shut it down. The brain began to die. It fought back at first, but they were too strong. Soon the fight was over. Chrístõ felt a twinge of guilt about the final coup de grâce. Killing anything was not something he took lightly. But this creature had been hurting people for too long. It had to be stopped.

Besides, he had realised something as he fought against its mind. Thesperus was not indigenous to this planet. It had come here all that time ago as a space born egg with a shell capable of surviving the heat of descent through the atmosphere and an impact with the ground that may well have begun the seismic shift that created the gorge. It installed itself below ground and waited for its food supply to come to it.

A parasite, and one that may have brothers on other worlds causing just as much harm to innocents.

“Riley,” he whispered aloud. He turned his mind back to those that had helped him. “Thank you. Violence does not come easy to any of you, either, but you did what had to be done. I must see to my friends, now.”

“May the love of Zost be upon you,” they answered. Then, just to prove that Time Lords weren’t the only ones who could move mountains with their minds, they created a new rock fall that buried the body of the Thesperus for eternity.

Chrístõ ran back to the Cavern of the Suns. He found Riley among those waking in confusion. He hugged him gratefully.

“I’m still engaged to a lovely girl,” Chrístõ assured him. “But I’m glad you’re all right.”

“I’m not complaining,” Riley answered. “What happened?”

“Long story.”

Inside the backpack Humphrey was wide awake, too, and noisily advertised himself.

“Sorry, old boy,” Chrístõ told him. “You stay put for a little while longer.”

He was still embracing Riley when the five times daily miracle of nature happened. One of the suns aligned with the right eye in the ceiling and bright, warm light filled the cavern, dazzling still confused eyes but filling hearts with unbounded joy.

The Minister of Zost who had been afflicted along with everyone else fond his voice as the light reached him. His prayer echoed around the cavern.

“All praise to Zost, bringer of light and of life.”

“Praise Zost,” Riley responded with the rest, despite his CofE roots and enjoyed Chrístõ’s embrace all the more.

Inside the backpack, Humphrey trilled his agreement and wobbled with shared joy.