"I know this area," Sammie exclaimed as the TARDIS crew stepped out into a warm summer morning. They all automatically turned to see the TARDIS disguised today as a blue-painted wooden gate set into a high wall of a dark-coloured stone. The symbol that made this more than just an ordinary gate was carved into the wood above the keyhole that was more than just an ordinary lock.

"Gritstone," Chrístõ said absently as he ran his hand over the stone. "A very hard form of limestone. Notice all the houses are built of it around here. The chameleon circuit works VERY well sometimes."

"This is Castleton," Sammie went on as they walked downhill to the solidly built village of gritstone cottages with slate roofs glinting in the sunshine. "In Derbyshire. My grandmother used to live here."

"She WILL live here," Terry told him. "Maybe in about 60 years." He nodded to where a carthorse attached to a brewer's dray stood patiently outside a public house called the Castle Inn. Beside it was what all of the group except Bo would have called a 'vintage' car. The only other traffic passing along the cobbled street between rows of neat slate-roofed grey cottages and small shops was a butcher's boy on a bicycle with a huge basket in front. They watched him huffing and puffing as he pedalled up the hill in his cloth cap and shirt sleeves rolled up. He and Sammie and Chrístõ were all in the same sort of shirts with collars that had taken them ten minutes of struggle to attach and waistcoats and jackets that seemed surplus to requirement in the summer sunshine. The girls were in dresses with tight bodices and wide skirts and wide hats that kept the sun from their faces.

"About 1900?" Terry guessed.

"Yes," Chrístõ said. "June 3rd, 1901, and it's just coming up to 12 noon. As if to prove him right the chimes of midday sounded in the clock tower of the village church.

"And the reason we are here?"

"Well, it was in my presets," he said. "But also because I'd like to look up an old friend. The TARDIS found his address here in the census records for me."

"Old friend?" Sammie looked at him. "How could you have a friend here - in this time I mean?"

"He trained to be a doctor with me and Elizabeth in London, in 1865."

"That was…" Cassie did a quick calculation. "That was thirty-six years ago. Your friend will be in his fifties."

"Fifty-five years old." Chrístõ said. "He didn't die until 1928. He lived a long, good life. As I always thought he would."

"He's going to be VERY surprised by you. He's aged 36 years and you…."

"Twelve noon," Terry said and looked meaningfully at the Castle Inn. "Lunchtime?"

"Yeah, why not," Chrístõ said with a grin.

Doctor Frederick Brett was enjoying a pint of local ale before he ordered his lunch when he chanced to look up and see a face he had almost but not quite forgotten. His memory jolted as he recalled his student days, too long ago for comfort, and the strange young man who disappeared overnight, leaving a message to his friends that was almost impossible to believe.

It couldn't be? If it was, then the message was NOT the product of a nervous breakdown as he had always tried to tell himself.

He stood up and approached the young man of no more than twenty years of age who stood by the bar looking around him with the curiosity about all things that Freddie remembered he always had. There were four other people with him, but he hardly took them in as he stood and approached his old friend.

"Chrístõ?" he asked tentatively. "Is it… could it be…"

"Freddie!" Chrístõ smiled brightly as he stretched out his hand to him. "This is luck. I was going to look you up this afternoon. Now you can join us for lunch."

"I should be delighted if you and your companions would join ME." Freddie signalled to the barman. Their party now numbering six they were quickly brought to a table in a private side room from the main bar, where the men were served ale and the ladies glasses of sherry while their meals were prepared.

"You haven't changed a bit," Chrístõ said to him. "Good old Freddie."

"Not true at all. I had far more hair and a much smaller waist size the last time we met," Freddie answered. "But you….." He paused and looked at his old friend. "It was true, wasn't it? You ARE a time traveller from another planet."

"Yes, I am," he said. "My friends are NOT from another planet, but they DO all come from different times." He introduced them all. Freddie shook hands with the men and kissed the hands of the ladies. He wondered exactly WHERE Chrístõ met one girl who looked like she came from the West Indies and another from China. Their youthful beauty made him feel his age though and that reminded him of the central problem that faced him when he looked back again at his old friend.

"Chrístõ…" Freddie began to speak and stopped. He was fifty-five years old. He had not seen his friend since he was 19.

He sighed in resignation. Whatever else he was, he was still his friend. "You're all right, that the main thing. We thought… when you disappeared. We thought all sorts of things. The note you sent to Elizabeth… She believed it. She really believed that you were what you said you were. But I thought…. I thought maybe…."

"I told Elizabeth the truth. You know that now, if you didn't before."

"Yes"

Their meal arrived. A beef stew that was nourishing though possibly a little heavy for a warm June day. Sophistication in pub lunches was still some 80 years away. The conversation was pleasant and friendly though. Freddie proved an easy man to talk to for them all. The fact that he KNEW Chrístõ's remarkable secret meant that they could all share with him something of the amazing life they led in his company. Freddie lapped up the stories of adventure on other planets and in other times.

"I feel such a dull old duffer," Freddie sighed. "I've done nothing but treat the ailments of this little town and grow fat and old. Elizabeth is a famous woman. You are… a hero my grandson would enjoy reading about in his boys' comic papers."

"You're a grandfather, Freddie?" Chrístõ smiled.

"Just the one yet," he said. "But I have four children, so my dynasty is likely to grow. My lady wife is in Buxton visiting my son at present. Hence my lunching out."

"I'm glad," Chrístõ said. "You lived the life we all expected you to live. You made a good living, a loving family. A good, solid, quiet life. Nothing to be ashamed of there."

"Chrístõ," Sammie said as he drank his ale, comparing it favourably to the commercial lagers he was more used to. "Can we go up to the cavern? I can't imagine coming here and not walking up past the Styx and exploring the Devil's Hole. I used to spend hours there when I stayed up here with my nan."

"Devil's Hole is not what the locals call it," Freddie said with a smile. "They've another word entirely."

"I know," Sammie shared the smile. "But my nan would have slapped me for using that word. And besides, there are ladies present."

"Of course we're going to see the cavern. It's why this place was in my presets."

"The Time Lords care about a cavern in Derbyshire?" Terry asked.

"Why not?" Sammie answered. "It's at least as good as the caves we saw on Betalon 8 - where we first met Humphrey. If they think you'd enjoy things like that, then this is a perfectly good choice."

Freddie came along too as they walked along the stream known as the Styx for no reason other than it emerged from the entrance to the Devil's cavern and somebody with a classical education had once had a sense of humour. Sammie was the most enthusiastic though as he led the way upstream, past a row of mining cottages where white linen proudly dried in the sunshine. Bo was at his side and he told her that his grandmother had lived in one of those cottages and that he had spent many happy childhood holidays there.

"I wish I could have taken you to meet her," he told her, squeezing her hand. "I know she'd have loved you."

"Well why not?" Freddie asked. "You are time travellers."

"Yes, but Nan doesn't know that, and she died when I was nineteen. History… has to stay happened. I should know that more than anyone."

Terry and Cassie looked at each other and said nothing. They both remembered the last bitter scene in Terry's parent's house. And Terry was fairly certain that his parents would have been just as unpleasant to Bo as they were to Cassie. Their prejudice against anyone not wholly British in their narrow perception of the word was absolute.

He wondered what they would make of Chrístõ!

Terry didn't worry much about his own family. They had disowned him effectively, but he did have some qualms about taking Cassie away from her mum and dad. They were nice people who would worry about her disappearing off the face of the planet. One day he would have to ask Chrístõ to take them to find her family and try to explain it all to them.

Chrístõ looked at his friends and felt their thoughts and nodded imperceptibly. Yes, one day they WOULD have to do that. He couldn't just take people from their lives without consequences. Terry and Cassie had first talked about spending the rest of their summer vacation with him. But they had been nearly a year now together in their own linear time and they no longer even talked about going back to 1969 and their university studies. They had grown away from those ordinary ambitions of people with their feet firmly on the Earth. He was glad of that, because he wanted them to stay with him for as long as possible. The thought of being alone again in his time machine saddened him. Now he had discovered how good it was to travel in company he just could not imagine going back to solitude. But they would have to face up to the consequences one of these days.

The cavern entrance was a great gaping hole in the sheer limestone rock face at the end of a gorge that Chrístõ suspected was the remains of an older cavern entrance that had collapsed. The size of it stunned even him. It was, his notes told him, the largest natural cave entrance in Britain and twentieth largest in the known galaxies. He doubted the local tour guide books would ever mention that last bit. They stepped past the abandoned and rusted frames of the rope-makers who had used the cave until twenty years ago when the lead-mining that was the local industry began to fail and no longer needed ropes.

"That's sad," Cassie said. "What do the people do now?"

"Many of them moved away into the big cities," Freddie told her. Manchester, Leeds, Sheffield. Some make a living mining Blue John for the jewellery trade and for tourists who come up here to view the caverns."

"Who is Blue John?" Bo asked.

"It's not a who, it's a what," Sammie told her. "A semi-precious stone that is found around here. Very pretty stuff. Not as valuable as Chrístõ's diamonds, but nice in its own way."

"We should definitely bring Humphrey here," Cassie said. And as Chrístõ reached in his pocket for his TARDIS key she grinned at Freddie. "Humphrey is both a WHO and a WHAT. He's a bit unusual but we're all really fond of him."

A bit unusual was a good description of the next few moments as far as Freddie was concerned. The sound of the TARDIS materialising echoed around the cavern making it seem louder than usual and the displacement of air was more noticeable than it was out in the open. Freddie gasped as a small wooden hut appeared at the mouth of the cavern with a sign on it saying - under the symbols - admission 1 shilling.

"The TARDIS thinks there should be an entrance fee for viewing the cavern," Chrístõ laughed as he went to open the door. He turned to Cassie and Bo and suggested they went in and found Humphrey. He, meanwhile, found torches and Sammie's night vision goggles. A few minutes later Freddie, who was still reeling from the arrival of the TARDIS and his one glance inside the door was even further amazed when Humphrey emerged flanked by the two girls.

"What…."

"This is Humphrey Boggart," Sammie said with a wide grin. "He's called that because I thought he was a boggart and Humphrey…"

"That's a twentieth century joke. Bo doesn't understand it either," Terry assured Freddie with a reassuring pat on the back.

"The name was not what was worrying me," Freddie said. "The APPEARANCE of this creature…"

"Humphrey is perfectly harmless," Cassie assured him. "In fact, he saved our lives not so long ago. He's a hero. And we all love him."

"Then I am honoured to meet such a hero," Freddie said, deciding that his life was far less mundane this afternoon than it had been since the last time he met Chrístõ, and meeting a creature that seemed to be an embodiment of darkness with a friendly smile was at least the final surprise of the day.

Or so he thought.

The strange party turned from the TARDIS and set off down into the caverns. At the bottom of the slope from the entrance they all had to bend low for a short walk, all except for Humphrey who shrank himself down to the right height to drift easily through to where the caves opened up again. There, as everyone stood and rubbed their backs they saw the perpetual misty waterfall that Sammie proudly told them gave this cavern the name of 'Roger Rain's House'.

"Humphrey isn't the only one stuck with a bad pun for a name," Cassie observed. She looked at Humphrey. He was, quite clearly, excited. He was darting about the cave like a pinball and emitting a chattering noise that was so obviously cheerful that nobody wanted to shut him up. Chrístõ calmed him enough to get an idea of what he was chattering about and he, too, became excited.

"He thinks there may be some of his own kind around the lower caves," he told his friends. "Humphrey, you lead the way."

Humphrey took him at his word and they followed him from the House of Roger Rain to the Great Cave, where Humphrey's noise bounced off the walls like a badly tuned orchestra, and then to a lower level to a high ceilinged cave called "Pluto's Dining Room." There, Humphrey's excitement went off the scale. Chrístõ told his friends to turn off their torches and he adjusted the one he had to a low-level green that matched the kind of light in Sammie's night-vision goggles.

"Oh my…." Cassie exclaimed and she heard Bo's indrawn breath, too. They both clung to their men as they looked around the cavern and realised it was FULL of creatures just like Humphrey. Chrístõ again calmed him a little, but his joy was almost a solid entity in itself and he was barely holding it in. He stood with his hands extended, palms up to show he meant no harm and was gratified when two of the dark creatures glided towards them. Strangely, they seemed to regard Humphrey as far more of a curiosity than Chrístõ or his companions. They were, he reasoned, used to Humans being in the caves either working or exploring for amusement. But Humphrey was a stranger of their own kind.

"Friend Chrístõ," Humphrey said. "Friend of all."

"I try to be," he said with a little laugh. "Humphrey, can your new friends talk to me?"

"Friend." One of the cavern boggarts, for want of any better name for them, shimmered slightly and moved closer as if examining him.

"Friend," Humphrey repeated. "Good, kind, friend Chrístõ."

"Friend," the cavern boggart said again and the word was echoed around the cave. When the susurration of their voices stopped Chrístõ spoke again.

"Are these ALL of your people?" he asked.

"All." The voice sounded sad this time.

"You were once more?" he asked. "Your clan is getting smaller?" As his friends watched awestruck Chrístõ listened and talked with the leader of the cave-dwelling creatures. And he heard something that dismayed him and made Humphrey wail plaintively. Bo and Cassie stepped forward to comfort their friend as Chrístõ related the problem.

"There's another cave lower than this one, and it has something in it that frightens our boggart clan." He laughed. "Really we MUST find a better name for them some day. But anyway, it seems this thing arrived here about a year ago and caused a lot of harm. It seems to have killed many of this clan that lived in the lower levels and now they're all hiding up here, hoping the thing stays away from them."

"What sort of thing?" Sammie asked.

"I am not sure. I'm having trouble with their description. They couldn't even send me a decent telepathic picture of what they've been up against." All he seemed to get from them was a sort of white light that caused a stabbing pain in his eyes. He rubbed his eyes and looked around at the earnest if ill-defined faces of the hundreds of creatures. They seemed many crowded around the cavern, but in fact they should have numbered thousands, not hundreds. They should have had the freedom of a whole cave system instead of being confined to one cavern.

Humphrey hovered at his side still and seemed to be looking at him with something like hero worship. Humphrey believed he could help his new friends. And because Humphrey believed, so did all the others. He looked back at his Human friends. They had much the same look.

"Help them," Bo said to him. "As you helped me. As you helped Sammie. As you help all who call out to you."

"I will try," he said. He looked at Sammie. "Do you know the way down?"

"Sure.. .this way." He led the way. Chrístõ followed. Humphrey went as if to go with him but the other creatures began to scream in panic. Chrístõ stopped and looked around. As they all thought of the same thing at once he rubbed his eyes at the bright light in his head and the stabbing pain behind his eyeballs.

"They seem to be saying," Bo told him. "They say Humphrey can't go with you or he will be….consumed…"

"Consumed?" Strange sort of word, Chrístõ thought, for a group of beings that otherwise used quite simple language.

"Yes….consumed. That's their word. It sounds as if…." She stopped. "I don't quite understand it, but the thing down there kills them, and they have no defence, and Humphrey shouldn't go down there."

"Humphrey," Chrístõ said kindly. "Stay here and look after the ladies and talk to your relatives. Terry and Sammie and I will try to find out what's going on down there."

"May I come, too," Freddie asked. "I'm not a hero, but I AM a doctor… if there is anything dangerous down there…"

Chrístõ looked at him and nodded. He doubted there was much that Freddie could do, but he was a level-headed man who wasn't likely to panic. He turned and headed down the sloping passage to the next level of the cave system, the one Sammie said was called the Devil's cellar. Sammie was just behind him in the narrow space where walking side by side was difficult. Terry and Freddie came behind them.

"Something down here has been killing creatures that are made of darkness." Sammie re-capped the situation. "WHAT can DO that? And can it kill us?"

"I don't know," Chrístõ told him. "Even though we've known Humphrey for months now, I'm ashamed to say I've never made an effort to find out WHAT he is. We've taken him for granted, got used to him being around and never really THOUGHT about him. Not EVEN when he was protecting us all. He's an entity made of darkness. But what IS darkness? Have you ever thought about that? Because I know I haven't. I always thought of it as an absence of light, not a thing in itself. I don't know what Humphrey is, so I don't know what can kill his kind. And I don't know if it is dangerous to us or not."

"But we're still going to find out."

"When you went out into the desert to do…whatever it is you were doing… you didn't know how many Iraqis had guns aimed at you."

"I didn't know how many Americans had guns aimed at me!" Sammie said with a grimace. "But yes, actually I DID have an idea how many guns the enemy had. We had intelligence reports. We could make a guess. We weighed up the risks. We NEVER took blind risks like this. We knew something of what we were getting into."

"You want to go back and wait with the girls?" Chrístõ asked him.

"I'm sticking by you, Chrístõ. But I just want to point out that this is NOT a calculated risk. It is a blind risk and it's not something I would take my men into."

"Well, as they say in the army - I take your remarks under advisement. But we're still going down here." Chrístõ felt irritated. But only because he knew Sammie was right. A professional military officer would not go into something like this with no information. But he was not a professional military officer. He was just doing his best the only way he knew how.

"And as I said, I'm sticking by you, Chrístõ. You're my C.O. until further notice and I'm right behind you."

"When you two have finished, could I point out that none of us is armed so all this military talk is pointless." Terry said.

"We're near the Devil's Cellar now." Sammie told them. "Just past this next bend."

"What's that noise?" Terry asked.

"The river we walked up earlier. It runs underneath the Cellar." They came out into the lowest cavern of the Devil's Hole system and the sound of the subterranean river filled their ears. The word eerie came to all their minds.

Something else came to Chrístõ's mind. He could feel something here. Something that was filled with fuming hatred. He shone his torch up and around the cave trying to see what it was that was so full of that one emotion that it overwhelmed his psychic senses.

"What…. is that?" Freddie said as the torch passed over something that they all knew at once shouldn't have been there. Chrístõ swept his light back over the thing. He might easily have missed it. It was nearly invisible, with a chameleon like camouflage. It was a snake like creature, some 10 metres long, maybe a metre around the thickest part of its body which was curled around the base of a stalagmite as thick as an oak tree.

"It's a basilisk," Terry said. And Chrístõ was surprised he knew that. On Earth they were considered to be mythological creatures. He was fairly sure Terry had never seen one before.

Neither had he. But he had heard of them. He knew that basilisk was the mythological name for them. The real name for them was a Ravoxian Serpent, because that was the planet they came from. How so many of them ended up on planets so many light years away nobody seemed to know, but the fact that they WERE a part of Earth mythology proved that many of them were on this planet. And he was looking at one now.

It WAS an animal. Not a sentient creature he could reason with. It was an animal. A dangerous wild animal.

"Everyone… keep very still and quiet," he said in a low voice that seemed loud all the same. "This thing CAN kill us. It's got poisonous fangs and it stores electricity in its body and discharges it into its prey." Chrístõ reached in his inside pocket and took out his sonic screwdriver.

"What are you going to do with that?" Sammie asked. "I thought it was a tool, not a weapon."

"I just put it into heat cutting tool mode. Cuts through rock. I left a message to myself on a wall in the 13th century BC that was still visible in 2000 AD. It will take that thing's head off…. If I can get close to it."

"You're going to kill it?" Terry asked. "Shouldn't you be trying to preserve it as a unique and endangered species or…

"It is a dangerous alien creature that doesn't belong here. I'm surprised there haven't been PEOPLE killed around here."

"There were some unusual incidents some years ago in the Speedwell caverns," Freddie said. "Miners who died of unexplained accidents. Those caves… it is believed that there are tunnels that connect the two systems. This thing… may have been moving between the caves for a long time."

"How does it kill the boggarts though?" Sammie asked. "They can't be bitten or electrocuted."

"I still don't know that," Chrístõ said. "Look, you guys back up out of here. There's no point in everyone being in its lair here. Terry, Freddie, go on back up the tunnel. Sammie….you watch my back but stay clear…."

Terry and Freddie turned back towards the tunnel as he stepped towards the creature, hoping it would stay asleep and inactive a few seconds longer.

It didn't. He was close enough to touch it when it raised its head and hissed menacingly, its forked tongue reaching out and missing his face by millimetres. He felt its malevolence like an entity in itself. He felt its eyes boring into him with nothing but hatred in its mind. He didn't quite understand why that was. It WAS an animal. And he didn't think he had ever come across an animal that was so focussed emotionally. Animals didn't HAVE emotions. They had instincts. That was the fundamental difference between sentient beings and animals. Sentient beings killed out of hate or greed or jealousy. Animals killed out of instinct and necessity. And the fact that this one killed out of hatred made it a singular animal, and all the more dangerous.

Yes, he had to kill it. Chrístõ knew that. It was a unique thing, but its uniqueness was it's malevolence. It had killed the most inoffensive creatures he had ever met in his life - those near relatives of Humphrey who were huddled in the cavern above in fear of it. And he knew what he had to do. There was no moral argument. There was no issue of 'endangered species'. Humphrey's relatives were the endangered species and this creature was endangering them.

He raised his hand and turned the sonic screwdriver towards the creature's neck, ready to sever it. But he misjudged his moment by a fraction and in the painful moment that followed he understood something he didn't know about Ravoxian Serpents before. As well as having a poisonous bite, as well as being able to electrocute their prey, they could produce from within their bodies the equivalent of a flash-bang stun grenade. That was what killed the darkness entities. The brightest light possible to produce without an actual supernova would destroy something made of darkness like being at ground zero of a nuclear blast would destroy flesh and blood.

He worked that out in the seconds before he slipped to the floor unconscious.

Sammie screamed as the blinding light stabbed at his eyes. Even when it was over he had purple spots in front of his eyes. He had used stun grenades, he had occasionally had them used on him. He fought against the disorientation and dived across the floor to reach Chrístõ before the creature, having knocked him down with the electric shock, turned its snarling and venomous jaw towards him. Sammie stared into the cold eyes. Not being telepathic he didn't feel the hate overwhelming him but he knew instinctively there was no reason for this creature to be alive.

He reached for the sonic screwdriver that had fallen from Chrístõ's hand as he fell, but to his surprise Freddie was there. His hand reached the tool first and he turned it on the creature. It must have been sheer luck that his finger closed over the switch that turned it on. Even more luck that when he turned it towards the creature it did what Chrístõ said it would do. It sheered through the thick scaly exo-skin and through the flesh and cartilage within and took the head off the creature. Terry reached them in time to be beside Sammie and pull Chrístõ out of the way of the heavy, falling dead creature.

It had all happened in less than a minute, from the flash, the electrical discharge, to Freddie acting on an instinct he didn't know he had.

A minute in which Chrístõ's two hearts had been stopped. Sammie's next move was to turn to his friend and examine him, and his own heart thudded in his chest as he realised the worst.

"He's dead," Terry cried.

"No," Sammie insisted as he pulled Chrístõ's clothes open and began to massage his left heart. "No, it's not too late yet. We can do this….CPR…."

"Both hearts." Terry reached out too, manually compressing Chrístõ's right heart in tandem with Sammie working on the left. After each fifteen compressions Sammie breathed into his mouth then resumed the compressions.

Freddie turned from his unexpected victory over a monstrous creature that had defeated his friend and watched in amazement what they were doing. He had heard them say that Chrístõ's heart - hearts? - were stopped and he didn't understand what they were doing. As far as he knew in his career, when a heart stopped, when two hearts stopped even, they stayed stopped.

Neither Sammie nor Terry had time to discuss it. For another long, agonising minute they were both too focussed to be aware of anything else. Then Freddie saw them both reach and clutch each other's hands in triumph. He saw Chrístõ's chest rise and fall as he breathed again. And Freddie revised everything he had ever thought he knew about the nature of life and death.

"Chrístõ," Sammie reached for his friend's hand and saw him open his eyes. "You're going to be ok."

"My…." Chrístõ spoke weakly. "My hearts…. hurt… what happened?"

"Your hearts had STOPPED. The thing shocked you and stopped both your hearts. You were dead."

"Feels like it," he said as he tried to sit up. "Did I get it?" The effort was too much for him yet. He lay back down again.

"No," Terry told him. "Freddie did."

"Freddie?" Chrístõ pulled himself up despite the weakness he felt and the dull ache in his chest that told him just how close to death he had come. He looked at his old friend who was standing there looking at him with wide eyed amazement.

"Chrístõ… you're alive."

"Yes. You killed the basilisk. Well done."

"Yes. But… you were dead. They said your heart…. Hearts…. had stopped. How? Is that because you're… not of this world."

"No. It's because they got to me quickly and did something that Humans of their time know how to do but my own people DON'T. I'd be dead if this happened on Gallifrey. I owe you guys. And Freddie… give me back the sonic screwdriver. It's a very dangerous tool if you don't know what to do with it."

"I think he did ok with it," Sammie told him. "Freddie, you're a hero."

Chrístõ stood up shakily. Terry and Sammie both helped him steady himself. He looked around at them, at Freddie and the dead creature.

"I nearly bit off more than I could chew," he said. "You guys… between you…. My people…. On Gallifrey…. They think Humans are weak, ineffectual, inferior. They are SO wrong."

"When you get back there, make sure you TELL them that," Sammie told him.

"When we get back up to the girls, DON'T tell them that we nearly LOST him," Terry said. They all looked at each other and silently agreed. Chrístõ gently moved their arms from his shoulders and walked forward unaided. No, they wouldn't talk of that, but he would never forget that he would be dead without them.

Freddie's heroic moment, though, would not be suppressed. The cavern creatures flocked around him as the story was told and his name became an eerie echo for a long time as they repeated it again and again. Humphrey pinballed about the place in joy because his old and new friends were all safe.

"Freddie," Chrístõ said. "You're the only person around here that knows these creatures exist. They live on darkness, but the thing they crave is company. That's why Humphrey's own clan died out. Their caves used to be busy places when Humans mined ore there. The creatures used to watch over the miners, like benign but invisible spirits. They loved them being there. But then the mines closed and the caves became a remote and rarely visited curiosity. The creatures died of loneliness. Don't let the same happen here. Come see them now and then. Encourage people to explore the caves. They won't make their presence known to strangers, but they will enjoy them being there. That's all they need."

"I would be glad to do so," Freddie said. "I am glad I could help them in their trouble. I am glad I had a chance to do something…. Something other than the mundane."

"Don't know about mundane," Chrístõ said. "I could use some days when something isn't trying to kill me."

As they walked up to the cave entrance the darkness creatures followed, their shadowy forms rippling around the walls.

"I think Freddie would enjoy a lift back to his office in the TARDIS," Chrístõ said. "Or does anyone think its close enough to teatime to stop off at the Castle Inn again?" That idea met with approval all around. Then they all turned and looked at Humphrey. Chrístõ was sharply reminded of the moment not long ago when he thought Sammie and Bo were going to leave him. He was surprised how similar this felt. He had taken Humphrey for granted, ignored his presence among them most days. But still, he had counted him as part of his adopted family on board the TARDIS.

"Come back and visit?" Humphrey asked.

"Well, yes, of course we will visit," Chrístõ said. "We'll come and see how you and your new friends are getting on."

"No," Humphrey insisted. "I come back and visit?"

Chrístõ looked at him as he hovered close to the TARDIS door.

"Humphrey wants to stay with us," Bo told him. "He wants us to bring him back here to visit his own kind, but WE are the ones he loves. And he wants to be with us."

Not for the first time Chrístõ wondered how something that consisted of condensed darkness felt anything, let alone love, and not for the first time concluded that love hade nothing to do with hearts. Hearts simply pumped blood around the body. Love came from the soul. And creatures made of condensed darkness had souls.

He had been educated for nearly 180 years, and he realised that he had not yet learnt everything.

"Humphrey, you can stay with us as long as you want. And welcome. The rule about the bathroom still stands though."