The TARDIS had unlimited space, and could create rooms to accommodate the needs of the crew. And yet, in the quiet times, everyone found themselves in the console room indulging their leisure pastimes. Chrístõ smiled to see it. At a table in one corner, Bo was teaching Cassie about Chinese aromatherapy. On a chair near them, Terry was practicing the guitar, playing along to Beatles songs on the CD player. On the other side of the console, looking slightly apart from the others, Sammie was oiling his side arm with quiet concentration. Chrístõ sat down with him as he worked.

"You ok?" he asked him.

"I…." Sammie looked at him and began to make a general kind of comment but then he decided the truth was better. "I miss being in the regiment. It hurts like hell knowing I can never go back. I AM glad to be alive. And… travelling with you, Chrístõ, is INCREDIBLE. I still can't get over the things we can do in this ship of yours. But I MISS my old life and its going to take a while." He looked about at his companions. "They're terrific. You're terrific. But you're not the sort of people I'm used to being around. I'm used to the sort of blokes who'd be down the pub with the lads betting who can down the fastest pint and maybe getting into a punch up with the sort of locals who like to pick a fight with a soldier to prove how hard he is. Can't imagine either you or Terry being up for that sort of thing."

"Well, got to admit it's not MY idea of an evening's entertainment," Chrístõ said. "IS that really you, or is it just what's expected of you as a soldier - the hard man act."

"It's what I'm used to." He knew that didn't answer Chrístõ's question at all. "Guess I have to get used to a different sort of life now."

"I hope you can feel happy with us."

"I'm trying," Sammie told him. "There is one thing… Tell me if I'm treading on dangerous territory. But one reason I was glad to stay with you guys… is…." He glanced at Bo, laughing at some joke with Cassie. "She looked after me when I was wounded. She spent a LOT of time with me. I really got kind of fond of her. And she seems to like being with me. But you and her SEEM to be a couple. And she has a way of looking at you. But YOU don't mind her being with me. The signals are pretty scrambled. And I sure would like to know if I'm heading for a fall where she's concerned."

"It's a long story," Chrístõ said. "And yes, you should know it. But we're not far off landing now. I'll fill you in later. That's a promise." He watched as Sammie finished reassembling his gun. "You shouldn't need that on this planet. We're just going to look at some interesting caves."

"Any chance that Epsilon one might be about"

"I hope not. But we didn't expect him in London either."

"As long as there's a chance, I'm bringing my gun. Terry told me what he did the last time you lot met him. He's the worst kind of scum."

"Well, you may as well know, Time Lords can't easily be killed by bullets. Our bodies can deal with something as simple as that. So if you're up against Epsilon, don't rely on the fact that you have a gun and he hasn't."

"Any chance there's a secret weakness in your sort that you'd reveal to me - an Achilles Heel I might take advantage of."

"Sorry," Chrístõ said with a laugh. "Even if I knew of one, I honestly couldn't tell you. That would be a betrayal of my own race."

"Good answer. You might have made a special forces man yourself, with training."

"I'm a pacifist."

"Could have fooled me," Sammie said.

Betalon 8 was listed in his presets as an uninhabited planet with impressive cave formations. It lived up to its description. Even the most amateur speleologist could easily reach the most spectacular caverns, lit by their own phosphorescence, glittering with the quartzlike minerals in the rock walls, and with stalagmites and stalactites of breathtaking size.

"Its like nature wanted to create something to rival architecture." Cassie summed it up that way. "Like it saw the Great Pyramids or Abu Simbel or one of our great Cathedrals and decided it could do just as good."

"I think nature had a head start," Terry answered her. "This began creating itself long before the pyramids were dreamed of by men. We wanted to rival nature."

"Maybe," Cassie said. She looked around. "Chrístõ? Where's Bo?"

Sammie and Chrístõ both looked at each other. She had come down into the cavern with them both, talking about training Sammie in the advanced forms of the Shaolin arts that they both knew. Sammie's martial arts was of the sort learnt by westerners, effective but far from the precision they aspired to.

"Bo?" Cassie shouted and at once the cavern was filled with her voice echoing off every wall. When they could all hear again Chrístõ gently suggested not doing that.

"Why don't you two go to the entrance in case she went outside," Sammie suggested to Cassie and Terry. "And Chrístõ and I will look down those passages."

"Why do we have to take the 'safe' route?" Terry complained.

"Because somebody HAS to look outside," Sammie answered. "And Chrístõ can see in the dark and I AM experienced at search and rescue. And I have these!" And he put on his army issue night vision goggles that he had brought with him for the darker parts of the caves. Despite being worried about Bo Cassie broke into fits of giggles when she saw him. The goggles had had that effect on her each time he used them and nothing he could tell her about night time incursions into enemy territory could make her see them as anything but an object of amusement.

"It's the best idea," Chrístõ said, and at that Cassie and Terry turned towards the main entrance to the cavern. He and Sammie set off down the dark tunnel at the side of the cavern, the only other place she could have gone.

"They don't really trust me yet," Sammie said as they walked. "Or is it because they look to you as their leader?"

"It's never really been about 'leadership'," Chrístõ said. "We're just friends. Doing stuff together."

Sammie wasn't sure that was true at all. Cassie and Terry both looked to Chrístõ whenever a decision was made. Even just then, it wasn't until he quietly said "It's the best idea," that they did what he suggested. And as for himself - Chrístõ LOOKED like a kid, but yet he had something about him that Sammie recognised as authority. He felt himself deferring to him automatically. It was as much as he could do not to call him 'sir' and salute him.

"I'm used to being in a chain of command," he said. "And used to being fairly well UP that chain, giving orders."

"Your plan was a good one," Chrístõ said again. "We ARE best equipped for this." And that was all he would say about that. Sammie had to admit he was diplomatic. He wasn't pulling rank and reminding him whose time and space travel machine they were knocking about in, or who had the superior intellect, or even that he was 160 years older than he was. Yet he knew Chrístõ WAS the leader of their company. It didn't need to be said. It didn't need to be signified with a uniform and pips on his shoulder. Chrístõ was a natural leader and it was for him to be his second in command.

"Well…" Sammie began to speak again but stopped when he heard what could only be Bo's voice echoing through the tunnel from up ahead. "Thank God! She's ok." He sprinted forward, surefooted with his artificially enhanced eyesight. Chrístõ was a few seconds behind.

But the tunnel split ahead and her voice had stopped again. Sammie made the decision instinctively.

"You take the left, I'll go right. If you don't reach her in ten minutes then it's the wrong path. Come back to here." His training and his natural sense of leadership and field command was taking over. Chrístõ deferred to his superior experience in this instance but was no less a leader for that - the more so, in fact, for being able to take his advice in an area where he had the superior experience. Chrístõ took the left tunnel.

Sammie headed to the right, moving quickly but not so quickly as to make him careless. The ground was not even and he didn't want a broken limb.

"Help!" He heard Bo's voice again. The English word was followed by a stream of her Chinese dialect. She sounded frightened. He didn't call out to her. The way sounds echoed in the tunnels it would be pointless. It wasn't even possible to judge how far away she was by the sound.

He turned a corner and there she was, hunched up by the cave wall, looking very sorry for herself. Her ankle was swollen and she was obviously in some pain. It was pitch dark, of course, and she didn't see him at first. She cried out in fear and tried to back away.

"Hey, Bo, it's me, Sammie." He lifted the night vision goggles that made his face looked odd and turned on his torch to illuminate her properly. She blinked in the light and looked up at his silhouette.

"Sammie?"

"Yes." He knelt by her side and examined her ankle. It was a very BAD sprain. But nothing they couldn't sort out back in the TARDIS. He lifted her in his arms.

"Thank you, Sammie," she whispered to him as she put her arms about his neck and rested her head on his shoulder. He liked that more than he was going to admit.

But she was only his so long as Chrístõ wasn't around, it seemed. He found him back at the junction between the two tunnels, he having come back when his search proved fruitless. When Bo saw him her eyes seemed to light up and Sammie let her down from his arms carefully. She managed to hobble the two steps that took her to Chrístõ's arms. Sammie looked on enviously as she kissed him as if they'd been apart for a week, not just a half hour or so. Yet Chrístõ's remarks earlier did suggest that he WAS in with a chance.

Chrístõ carried her out of the cave. Sammie noticed that she hardly seemed any weight in his arms. He really WAS stronger than any Human, even him, and he'd been trained to march for mile upon mile with weight on his back.

Cassie and Terry were relieved when they emerged into the light of the cave entrance. Both of them were sitting on a rock by the TARDIS, waiting for further news or instructions.

"Oh, I knew you'd find her," Cassie said to Chrístõ as Terry opened the TARDIS door for him to bring her inside.

"Sammie found her," he corrected her.

"Thanks, Sammie," Cassie said with a genuine smile for him. Then she turned her attention to Bo as Chrístõ laid her on the cabin bed. He took her shoes off to reveal a very badly swollen ankle. He put his hands on the swelling and she flinched at first but then felt a lot better as he seemed to draw out the heat of it into his own cool hands.

"We made an ointment for this sort of thing," Cassie said and sprinted over to where their aromatherapy experiments were still set out on the table. She looked at the jars and puzzled over them for a minute. She came back and gave one of them to Chrístõ. "I think that's the right one. Bo labelled them and it seems I need to learn Mandarin as WELL as Chinese medicine!" She went to the cupboard under the console that contained a more conventional medical box and as Chrístõ applied the ointment she wound a bandage tightly around Bo's foot.

"You'll be ok now," Chrístõ told her. "But why did you go off like that in the first place? We were worried."

"I saw something. A… a thing… something that made me want to follow it. It seemed to want me to follow it."

"White rabbit?" Terry asked and Chrístõ smiled.

"Alice down the rabbit hole? I don't think so. What sort of thing? Can you tell me anything else?"

"It seemed kind," she said. "I thought so at first. But I was frightened after a while because it was dark. Then I tripped and I lost sight of it."

"Sounds like a boggart," Sammie said. Everyone looked at him. It was the last thing they expected somebody like him to say. He grinned sheepishly. "Where I come from - East Lancashire - we have legends of boggarts - well, kids stories really. My mam used to tell me about them when I was little. They live in holes out on the moors, and lure unwary people astray, just out of maliciousness."

"That DOES sound like what I saw," Bo said. "We have a story like it in China, too."

"I expect every culture in the universe has something similar," Chrístõ said. "We're a long way from East Lancashire though. And don't worry, your secret is safe with us. Nobody who knows you as Lieutenant Sammie Thomlinson of the SAS will ever know you once lay awake at night afraid the boggarts were going to get you."

Sammie looked rather disturbed by that disclosure.

"That wasn't fair," Terry admonished Chrístõ. "Reading his secret thoughts like that."

"No, you're right, it isn't," he admitted. "Sorry, Sammie. That WAS mean of me."

"That's ok," he said. "Funny, I haven't thought of those things for years. I'm certainly not scared of them now."

"When you've hung out with Chrístõ a bit longer, you'll find boggarts aren't much to worry about," Terry said. "Flesh eating space cannibal ghouls were the first thing we got to know in his company."

"Oh don't remind me!" Cassie said with a shudder.

"Never mind that sort of thing now," Chrístõ said. "Bo, precious, you lie down and try to sleep. You've had a bit of a shock and you ought to sleep a bit." He tucked her into the bed and kissed her gently on the forehead. She closed her eyes dutifully. He went to the console and put them into temporal orbit then he turned to Sammie.

"Come on with me. While we've got a bit of free time I want to start on your training."

He DID want to start teaching Sammie the finer points of Eastern martial arts. But he also wanted to talk to him about Bo. They both changed into the loose fitting gi and Chrístõ began with some Tai Chi moves. As he challenged Sammie to match him in the movements he told him the story of how they had found Bo as the semi-drugged, beaten and deeply miserable sex slave of the cruel Lord Marley. He gave a brief description of how he had fought Marley and freed her from him, freed her body of the drugs and repaired the scars on her body.

"But the scars in her head, I can't do anything about. She's recovered pretty well physically. She's remembered all her old skills as a Shaolin. She's rediscovered a lot of her culture and adapted to this wandering life of ours. But she's still vulnerable. And I've tried to show her that love can be a gentle thing, a thing that asks nothing of her."

"You're not… you don't have a sexual relationship with her?" Sammie looked at Chrístõ. "Is that a stupid question. I forget you're not even Human. CAN you have that sort of relationship?"

"Yes, I can," he said. "We are not THAT different from you. My mother was Human. But no, Bo and I are not. She does love me very deeply and I love her. But it is not sexual. Quite apart from her having enough of that from Marley, and apart from the fact that I come from a culture where we NEVER do that outside of marriage anyway, it would be wrong of me to lead her on that way when I know we're not meant to be together." He explained Li Tuo's reading of her future to him. Sammie looked a little sceptical.

"Seriously…. Because of a fortune teller, you don't think you can make a move on her. And she practically giving herself to you with all of her body language?"

"Seriously. And Li Tuo is not just a fortune teller. If he believes Bo is destined to love another man, then it is my responsibility to look after her until that man who is destined to make her happy comes along."

"And who would that be?" Sammie asked.

"Not somebody whose idea of sophistication is a drinking session and a punch up," Chrístõ said coolly.

"Oh." Sammie looked disappointed. His hopes were shot down in flames by that one comment. "I guess I kind of hoped…"

"You misunderstood me," Chrístõ said as he moved into a higher level of the Tai Chi exercise requiring Sammie to watch and learn quickly. "I'm not saying you AREN'T right for her. I'm saying that you should look at your priorities. What matters most to you? Vicarious pleasures like those or the love of a beautiful and special woman like Hui Ying Bo Juan."

"You really think I'm in with a chance?" Sammie asked.

"I'm not going to push her your way," Chrístõ said. "She loves me a lot. And I love her. And I'm not saying I can give her up easily. It will hurt no matter who wins her over. But she is interested in you. And I think you know what you have to do. I know what I have to do…. Which is NOT stand in the way of the right man to make her happy."

"But…." Sammie still felt he was getting mixed signals. What Chrístõ had told him, in all but the plain words, was that HE was the man Bo was destined to be with and that he should put his mind to seducing her away from the man she thought she loved - Chrístõ. If he had ever disbelieved it, now he KNEW Chrístõ was from another planet. No man on Earth would give another man permission to steal his girlfriend from him.

"Just give it time," Chrístõ said. "She…" Whatever he was about to say went unsaid. A scream reached them even within the dojo with its walls designed to keep out intrusive sounds and allow for perfect concentration.

"That's Cassie," he said and in the same breath he was sprinting for the door. He, Sammie and Terry, from the other direction all reached her at the same time. She was standing by the bathroom door looking as white as a sheet.

"What happened?" Chrístõ asked her quickly.

"I saw something in there…. I think it was the…. The boggart…."

"What?" Terry put his arms around her in comfort. "But…"

"Could something have got on board with us?" Sammie asked. "We had the door open for quite a while. We were more concerned about Bo."

"The TARDIS SHOULD have alarms and alerts to prevent that sort of thing" Chrístõ said. "Unless this entity is so unusual it just didn't recognise it. Couldn't rule that out. After all nobody else saw the thing Bo thought was luring her away. Which way did it go?"

"That way," Cassie said, pointing down the corridor.

That way is miles of corridor,” Sammie said. “I WALKED them looking for Iraqis."

“Not exactly miles,” Terry contradicted him. “But chasing around them not knowing what we’re looking for is pretty pointless.”

"Ok," Chrístõ decided. "Let's go back to the console room right now and think about this."

Bo WAS asleep. Chrístõ was satisfied to leave her sleeping. She'd be better for it in the end. Cassie sat next to her. That was satisfactory, too, because although he did not believe for one minute that women were the weaker sex, he did think there were some things best left to men, and stalking the corridors of the TARDIS looking for invisible entities was one of them.

"What are you doing?" Terry asked him.

"Trying to get the life signs scanner to recognise a life sign it didn't recognise before."

"Right. And is it?"

"Not yet," he said biting the tip of his tongue as he made fine adjustments to two dials either side of the life support monitor. "Ah… Interesting."

"Yes?"

"Our 'boggart' seems to be an entity made up of what I could only call condensed darkness. It's not the best or most accurate technical term, but it'll do."

"You've actually found it?"

"It's in the corridor by the secondary console room. It's dark down there. That area hardly gets used and some of the lights don't work.

"Is this where we get to ask how many Time Lords it takes to change a lightbulb?" Sammie asked. Chrístõ laughed but Terry looked at him with a puzzled expression.

"Your 80s joke missed its mark with the 60s children," Chrístõ said. "And I'm afraid the only answer I can think of anyway is one Time Lord as long as he has a couple of Human friends to hold the ladder. And even more boringly it should probably be 'how many Time Lords does it take to remember to stock up on spare bulbs." Sammie laughed. Terry still didn't get it. Chrístõ wasn't surprised. The light bulb jokes had a VERY limited lifespan.

"Anyway," he said briskly. "Looks like the hunt is on. Sammie, you have a communications headset among your kit?" Sammie found what they needed quickly. "Ok. Just got to patch the frequency through to the TARDIS and Cassie can come over here and be our spotter on the display." Cassie came dutifully to his side and he showed her the dark pattern that was affectionately nicknamed the 'boggart' and the brighter dots that were themselves in the console room. "Let us know if it moves on or if we're closing in."

They set off into the mysterious corridors of the TARDIS of which Terry knew half a dozen, Sammie even less. They both wondered if Chrístõ really knew them all.

"Yes," he said. "It's MY TARDIS after all."

"It's bigger than a battleship," Sammie said. "How come it needs so much space?"

"Never know what it might need to provide for the crew. I have a dojo and a library, kitchen, bathroom, bedrooms for you guys. Those are the rooms we live in. Then there is the swimming pool, and the cloister room, where the power source of the TARDIS is kept, the engine room and the backup console room. But there are loads of possibilities. The TARDIS reads our needs and creates rooms for us."

"I could use a practice range," Sammie said. "Shooting practice - could it…"

"Probably. Though it knows I don't really like the idea of guns. Might not be TOO receptive to the idea."

"It does what you say? The TARDIS?" Sammie asked him.

"Most of the time. It has a symbiotic relationship with me. It recognises my needs - and that of my companions too. But it can be a bit fussy. It's female, I think."

"That would explain a lot," Sammie laughed.

"You're getting near," Cassie said in his headset. "Around the next corner…. It's just sitting there at the moment."

"We're close," Sammie whispered and he went into 'stealth mode' edging along to the corner close to the wall before launching himself into the gap. As Terry and Chrístõ caught up with him he opened fire. The corridor echoed with the sound of the two shots fired in quick succession. Sammie looked startled when Chrístõ dived in front of him. When all three of them had recovered from the shock to their aural systems Terry rounded on him.

"That was bloody stupid."

"I saw something," Sammie said. "I made a judgement call."

"Yeah… shoot first and asked questions later. Typical soldier."

"I'm not…."

"Yeah, looks like it." He shone his torch on the empty wall and muttered 'trigger happy."

"I am NOT trigger happy," Sammie protested. "Typical of somebody like you. You've read all the bad stories. You think soldiers are just mindless killing machines. You never think you wouldn't have a chance to be a flower-power peacenik if people like me didn't fight for YOUR peace."

"Hey, man, that's not what I mean," he replied. "But you know what they say - if the shoe fits. And you were quick to jump on the defensive."

"The shoe doesn't bloody fit." Sammie turned on Terry, a fist raised.

"Come on then, SAS man, you think that's the answer to everything, I can stand my own corner. After the stuff I've seen and done with Chrístõ the past eight months."

"Enough!" Chrístõ said, coming between them. "Both of you. Sammie, these passages are too narrow for handguns, anyway. And I'm not sure if the entity is even hostile. Its more likely frightened. Especially if it has any aural nerves."

"I'm not a peacenik." Terry said again.

"I'm not trigger happy."

"I'm not somebody who enjoys causing others pain," Chrístõ said. "But if you don't both shut up there's a nerve in the back of your necks I can press with three fingers that will make you wish you never met me. And Sammie…." He opened his hands to reveal in each a misshapen bullet that had ricocheted off the impenetrable TARDIS wall and would both have hit him if Chrístõ had not caught them.

"Good God!" he whispered in awe. "What are the walls made of? What are YOU made of?"

"The walls are made of Pentaluminum. An alloy not unlike aluminium but many times stronger. I'm made of flesh and blood. And yes, that did hurt." They just glimpsed the burn marks on his hands before his remarkable regenerative ability easily repaired the minor damage.

"If you are at all interested," Cassie said down the earpiece to Sammie. "The entity has now retreated even deeper into the corridors."

"Ok, I get the message, no more shooting," Sammie said and repeated Cassie's message to the others.

"I guess it DOES have aural nerves," Terry said. "By the way, have you thought - the TARDIS is just like its home - the big cavern is like the console room. And these corridors are like the tunnels."

"Good point," Sammie conceded.

"Its home was darker," Chrístõ said. "It must be disorientated even though much seems familiar to it."

"Maybe we should turn the lights out," Terry suggested.

"Not a bad idea," Chrístõ nodded. "And we're well positioned to do just that." He opened a door and the others followed him inside. They stared around at an exact duplicate of the console room except somehow it had a 'new' look to it and seemed unlived in. The room they were used to had those touches like the sofa and worktables and Bo's cabin bed, and the console had post-it notes here and there with notes to himself written in Chrístõ's strange alien language which, after a couple of trips in the TARDIS everyone found themselves able to translate easily.

Chrístõ went to the console and fired up the environmental control segment which was otherwise dark and quiet. He pressed keys on the keypad rapidly. Watching Chrístõ type would make the most impressively qualified secretary weep. When he was finished and pressed "send" with a final flourish the lights in the room immediately changed from white to a kind of shadowy low-level green. Sammie gave a startled cry. He was still using the night sight goggles and found himself unable to see through them. He pulled them off and was startled to find the light around him exactly the same as through the goggles.

"You SAW the entity with night vision. I know the girls both saw it without any aid, but neither of them saw more than vague glimpses. I think the only way to see it properly is with night sight. You okay Terry?"

"Yeah. This just takes some getting used to. How do you recognise the enemy when you see this way?"

"They're the ones shooting at you." Sammie replied. He was still slightly smarting from the argument earlier and the realisation that he HAD fired his weapon inappropriately and would have paid the price for it if he had not been in company with a Time Lord. He was still amazed that even an ALIEN could catch two bullets in his bare hands. Chrístõ was a man of many surprises.

"Its coming back towards you," Cassie warned them. "Moving quite fast now. I think it likes the new lighting. Can't say I fancy it though."

"Its coming towards us," Sammie repeated.

"Ok, quietly," Chrístõ said. "You two come behind me. If it IS hostile, I bleed less than you do."

Chrístõ stepped out of the back up room and into the corridor. The other two moved quietly behind him.

"Cassie said it's right round the next corner," Sammie whispered. "Heading our way."

"Ok." Chrístõ stopped and waved to the others to do the same. They hardly breathed as they waited, Cassie whispering to Sammie that it was getting closer.

When it turned the corner they were all surprised. Chrístõ was surprised that his description of it as condensed darkness was so accurate. Sammie was surprised that he ever thought he could shoot it. Although it had dimensions of height and width and depth, it was, at the same time, a creature of no solid substance. A bullet couldn't possibly harm it. Terry was surprised at how non-threatening it looked. Its eyes - patches that seemed even darker than the rest - were big and somehow appealing. Its mouth was an upturned curve that might have been a smile. It looked like a dark moon gliding along in front of them, about knee height.

"Can you understand me?" Chrístõ asked it. The 'boggart's' eyes seemed to blink and then it 'spoke' in a whisper that did not come from its mouth, which maintained the 'smile' but from all around it.

"Understand you."

"Then can you understand that we mean you no harm. We only pursued you because this is our ship and you do not belong here. We wanted to return you to the cave you belong in."

"Do not belong there. No longer. Last of kind. Lonely."

"What happened to the others?"

"Faded away."

"Will you fade away?"

"Don't want to. Lonely. Want friends."

"You want US to be your friends?"

"Yes."

"But you can't come with us," Terry said. "This is a time and space ship."

"This is like home. But with life." The boggart seemed to shimmer for a moment. "Like being among life. Do not wish to harm, frighten. Wish to be among life."

"Is it on the level?" Sammie asked suspiciously. "Can we trust it?"

"I think so," Chrístõ said. "I can sense no malevolence from it. It genuinely seems to want to be friends with us." He looked at it again. "Follow us," he said. And he turned and walked in the direction of the main console room. The boggart followed him. Terry and Sammie looked at each other in surprise then shrugged and took up the rear of the strangest party they were yet a part of even in the weird world Chrístõ had introduced them to.

When he reached the main console room he was surprised to find Bo standing beside Cassie at the console. Both of them were startled as they looked at the boggart.

"Come," he said reaching his hands towards the girls as he moved to the sofa. They came and sat next to him, looking with wide eyes at the boggart as it hovered in front of them. Sammie and Terry remained standing on the other side of the creature.

"We have had a communications problem from the start," Chrístõ said. “Humphrey here just wanted to be friends, but until he had absorbed enough of the TARDIS’s ambience to be able to express himself in a spoken language we couldn’t understand that.”

"Humphrey?" Terry asked.

"Humphrey Boggart?" Chrístõ smiled disarmingly. "If you're going to join us, you need a name," he said to the creature. It shimmered again and repeated the unfamiliar syllables.

"Hum…phrey."

"Yes?"

"Yesss." It said.

"Humphrey is lonely. He wants to travel with us. I can't think of a single reason why not. He seems quite comfortable wandering the depths of our corridors. And now you can all see he is nothing to be afraid of."

"I think he's adorable," Cassie said with a broad smile. Bo laughed and reached as if to touch Humphrey. He backed away with a shimmer at first, then moved closer. Her hands passed through his insubstantial form but she just smiled joyfully.

"He is a good creature," she declared. "There is no bad in him."

"My mam would be surprised. Me travelling with a boggart." Sammie said.

"So… your mum would be ok about you being in a space-time machine with an alien with two hearts, but the boggart would bother her?" Terry summed it up. Sammie grinned.

"Well, when you put it that way…."

"Seems like we're all agreed that Humphrey can stay," Chrístõ said. He stood up and went to the console. The creature drifted there with him. "We need to set some rules though, Humphrey. I can't keep the lights like this everywhere. I can set it so that the lower levels are kept this way for you. The rest of the corridors will have ordinary lights. Which I think means we won't be able to see you. Am I right?"

"Yes."

"Ok, then on your word of honour as a boggart, you have to promise to stay out of the bathroom when anyone is in there - especially the girls. Because that's just not polite. And I think we'd prefer you not to go into the bedrooms either. Otherwise, you're free to wander about the TARDIS just like any other member of the crew. For as long as you want. If you want to come back to your own cave, tell me and we can come back here. Or if we find any of your own kind somewhere else…."

"Thank you," Humphrey whispered. Chrístõ adjusted the lights to normal and he disappeared but they could still hear his voice as he moved towards the corridor. Cassie and Bo came to the console and watched him move back to the lower section of the TARDIS where they didn't go very often. They saw him stop by the doorway to the back up console room and Bo said she thought he would nest there.

"I think he will," Chrístõ said. "As long as he sticks to the rule about the bathroom, he'll be all right."