Robert Campbell watched his grandson at the controls of his remarkable ship and then turned to look at the viewscreen. The swirling image that Davie said was the time vortex resolved into a view over a wide lake with a single rowing boat causing ripples in the mirror surface.

“This is another planet?” he asked. “It looks like Scotland.”

“I always think this part of Tibora looks like southern Canada,” Davie answered.

“Southern Canada looks a lot like Scotland,” Robert answered. “But I expected another planet to be a little different.”

“If you want that sort of thing there are more exotic places in the galaxy: Planet One, the Metebelis planets.... SangC’lune would blow your mind, especially when the people realise you’re MY blood kin. They would treat you like a god.”

“I don’t think I would want that,” Robert said. “Do they think YOU are...”

“Just a bit,” Davie admitted. “They do here, too. But they’re a little less demonstrative about it. Brenda’s mother generally worships me with food. You’ll like Mr and Mrs Freeman. They’re good people. Hard-working country people.”

“Brenda is a fine young woman,” Robert agreed. “I look forward to meeting her family.”

“That won’t take long,” Davie said, noting the figure running along the lakeside towards the TARDIS. He moved towards the door and opened it as Brenda’s younger brother, Phillip, reached it.

“Hey, kid,” he said cheerfully. “How are you?”

“Better now you’re here,” the boy replied. “Davie, I’m so glad you came. Come on. Mum and dad are waiting.”

Davie stepped out of the TARDIS, noting its disguise as a humble fishing hut, belying his status as one of the honoured Lords of Time. Robert stepped out after him. He matched Davie’s step as they headed towards the substantial log built dormer bungalow where the Freeman family had lived for several generations in harmony with their environment. Mr Freeman was a Steward of the Mountain, responsible for the wildlife that made its home around the dormant volcano and that crystal lake.

The front door was opened even before he reached it. Davie had never had to knock on that door even before he married the daughter of the family. He was always greeted warmly by Mr Freeman, who met him on the threshold.

He didn’t bow to him. He had persuaded him that such obeisance was unnecessary. Instead he shook hands warmly.

“Marcus,” Davie said, using his father-in-law’s first name, something he had never done before he was married to Brenda. “I would like you to meet my paternal grandfather, Robert Campbell.”

Marcus Freeman looked as if he was about to forget himself and bow to the grandfather of a Lord of Time. Then the two men shook hands before Mr Freeman invited his guests into his house. Mrs Freeman was effusive in her greeting to her daughter’s Time Lord husband and quite astonished to meet his kin. They were soon seated in the drawing room and being plied with tea and sandwiches.

“Doreen,” Davie said gently to her after a while. “Robert is from my father’s people. You don’t have to genuflect to him. He is quite happy with a cup of tea for now. Later, Marcus could open a bottle of Northern Tiboran Malt, and that’s as much of an offering as he needs.”

“He’s blood kin to you,” she said in justification of her behaviour. Then she changed the subject quickly. “What about my daughter? Is she really as well as she says when we talk on the videophone?”

“She’s doing very well,” Davie assured her. “If there had been any doubt, I would have come for you sooner. As it is, with a month to go, she is ready for her mother to be with her, despite all the women of our family around her. My mother is spending so much time in our apartment my father is starting to feel neglected at home.”

“I look forward to travelling to Earth tomorrow. But for tonight, you and your grandfather are our guests. Let me offer you the best of hospitality.”

Davie accepted those terms. He allowed her to make drinks and snacks for him and Robert and then, at the appropriate time, piled the table high with food for a sumptuous supper.

After supper, Marcus opened a bottle of the local liquor, and Robert Campbell considered it to be equal to the best whiskey made in his native Scotland. Davie took a glass of it, too, as he talked to Mrs Freeman about Brenda and to her husband about the interesting work he did as Steward of the Mountain. They were getting ready for what was promising to be a good tourist season, now that angling and water sports were safe on the lake again and everyone whose livelihood depended on that was optimistic.

Robert Campbell listened for a while. Before the Dalek invasion the issues that concerned Marcus Freeman were very much the same issues that concerned him. He was struck by the fact that he was on a planet whose sun was barely visible from Earth, but the people here not only looked the same, but lived the same way. The only extra-terrestrials he had met, other than his own daughter in law and her family, were the Daleks, so it was a relief to discover such commonality with other people.

Sometime in the course of the evening the conversation turned onto Davie’s adventures as a traveller among the stars. Robert noted that his grandson never bragged about his actions, and he didn’t glamorous the danger he had frequently been in, especially with the Freeman boy listening avidly. But he gave the impression of one who would not walk away from a fight.

“I do worry about that,” Mrs Freeman said. “Davie... I understand that you had to fight against those fiends who tried to invade your world. But... when it is another planet... when it isn’t your own people... must you always put yourself into danger...”

“Yes, I must,” Davie answered. “I am a Time Lord. That is more than just an empty title. I am responsible for the wellbeing of the galaxy... of people who can’t fight for themselves. Earth is my special responsibility. And SangC’lune... Tibora, too. As a dominion of Gallifrey I am duty bound to protect this planet.”

“Why should anyone want to invade Tibora?” Mrs Freeman asked. “We have nothing of interest to them.”

“I would have said the same about Earth until the Daleks came,” Robert answered her. “Davie is right. He has the duty. And I’m proud of him for shouldering that responsibility. You should be, too.”

“I am,” Mrs Freeman admitted. “I worry for him, though. And for Brenda. Should anything happen to him...”

“My life is much less fragile than that of other races,” Davie pointed out. “I can take risks others can’t. But I’m not reckless. I calculate those risks. And nothing is more important than staying alive to return to Brenda... and to my children.”

That satisfied her, and brought the subject of conversation back around to Brenda and the impending birth of the twins. As much as that prospect excited him, too, Robert was distracted by the quiet withdrawal of the boy, Phillip, from the conversation and from the room. A father’s instinct told him there was something wrong, something Phillip’s own parents had missed in their anxiety to give their attention to Davie.

Robert quietly got up from his comfortable chair and followed the boy. He found him outside on the wooden veranda overlooking the lake. It was dark now, and the water was a black void except where the moon was reflected from it. The night was cold, but the veranda had heaters powered by solar energy stored in the daylight hours.

Phillip was crying softly. That was the clue for Robert that something was really wrong. A boy who wanted attention would have been crying loudly, in front of his parents.

“What’s the matter, son?” Robert asked, stepping closer. The boy looked up at him and wiped his eyes, but there was no disguising the fact that he was crying. “It’s all right. You can trust me. I’m a grandfather. I’m a great grandfather, since my other grandson has a wee baby boy already. Do you have grandparents, Phillip?”

“They live in the city,” Phillip answered. “I only see them on holidays. And they can’t help me now. I thought... I thought Davie would. But... but he can’t see it. I thought he was clever. I thought... I was sure... he would... but he can’t see...”

“See what?” Robert asked. Then he listened in horror as the boy told him. He didn’t waste any breath disbelieving him. He gave him a reassuring hug around the shoulders then stood up and went back into the house.

“Davie,” he said. “Phillip was just telling me there’s a rather spectacular meteor shower due tonight. He also says you’re the man to tell us all about that kind of thing. Would you care to take a walk with us before bedtime?”

“I could do with stretching my legs,” Davie admitted. He stood up and nodded to Marcus Freeman. “We’ll be glad to take another dram of your malt when we get back.”

“You’ll be more than welcome,” he answered. Davie found his coat and followed Robert outside. Phillip fell in step alongside him. They walked down towards the lake, well away from the house before the boy spoke.

“That’s not my dad,” he said. “It looks like him, and sounds like him. But it’s not. And don’t tell me I’m being stupid. I know my dad. And it’s not him. And he’s not the only one. Three nights ago something came down in the forest with a smash. Dad and Mr Favia, Curt Hanover, Berr Langham and Dan Bannon went to make sure there was no fire and to find out what it was. They didn’t get back till dawn the next morning. Mum was too relieved to see him to ask questions. But I knew. Aliens have copied my dad. And I think I know why. They know about you, Davie. They know you’re a Time Lord, and they know about your TARDIS. And Earth. They want you to take him to Earth in the TARDIS and then they can take that planet over, too.”

It could have been the far-fetched idea of a teenager with a vivid imagination. But Davie, like Robert, didn’t waste time disbelieving him.

“I don’t know what the motive is, yet,” Davie said. “I’ll keep an open mind on that, for now. But you’re absolutely right, Phillip. That’s not your dad. I knew something was wrong straight away. I’ve been waiting for an opportunity to do something about it.”

“Then what...”

“It’s a metamorphic creature using his pattern. Cleverly done. The personality, the memories are all intact. But I could tell. It’s a good job Stuart isn’t here. He’d be climbing the walls from the smell. I’m nowhere near as good as him, but the earthy, damp iron smell is unmistakable.”

Phillip’s face visibly paled in the moonlight. Robert reached out to him reassuringly.

“Davie, have a little heart. You’re talking in such a matter of fact way about a creature that murdered his father to take over his body...”

“Not murdered,” Davie assured them both. “There are many species that metamorphose. But of the three that smell like iron, they all need to keep the specimen... sorry, Phillip, that’s not the best word for it... they need to keep your dad alive, to access his brain patterns. Otherwise the copy couldn’t be maintained. He’s alive and he won’t be far away.”

“We’re going to find him?” Phillip asked, his voice filled with cautious relief.

“We?” Robert was uncertain. “Not the lad, surely?”

“It’s my dad who’s missing,” Phillip pointed out.

“I don’t know who we can trust. All the local men who might form a search party were with Marcus. Chances are they’re copies, too. The three of us are on our own. It’s not ideal. But you never shied away from the fight when you were up against the Daleks, Robert. I know I can count on you. And Phillip is young, but it’s his dad, his friends, his world that is under threat. You can’t expect him to stand idly by.”

“You’ve got a point, there,” Robert conceded. “All the same, if there’s any real danger...”

“Phillip is our local guide. When it comes to any actual fighting... well, you both leave that to me. Phillip... can you find the place where the ‘thing’ came down two nights ago? I know it’s dark, but you grew up here...”

Technically that wasn’t true. Phillip was a changeling left with the Freeman family a year ago by aliens who needed to find homes for their orphans. But he had the memories embedded in him of a boy who had explored the forest from an early age.

“It was near the Crystal Falls,” he said. “I can show you. Me and Lizzie and Ger Bannon usually play there. But dad... the alien pretending to be dad... said I wasn’t to go there any more. That’s one reason why...”

“Show us,” Davie said. “Robert, are you all right for a night walk in the woods?”

“I hope you’re not implying that I’m an auld-faither who can’t keep up with you young ‘uns.” Robert slipped into a broader Scots dialet in his indignation.

“I was,” Davie admitted. “But I stand corrected.”

Phillip was impatient. Several times Davie called him back because he was too far ahead of them.

“You don’t know how many there are,” he reminded him. “We want to rescue your father, not fall into a trap.”

“What sort of aliens might it be?” Phillip asked.

“I’ve narrowed it down to two possibilities,” Davie replied. “It’s either a Yamelien, or the Zygon. And of those... Yamelien are the universe’s hired mercenaries. They tend to work alone. If so many men were taken, I’m thinking its more likely to be the Zygon. And that actually goes with your theory about them wanting my TARDIS technology. It also makes sense that they came to a place like this. The lake would be ideal for their purposes...”

Davie stopped talking. He pushed Phillip behind one of the pine trees at the edge of the forest. He nudged Robert behind another. He concealed himself carefully and waited. The shadowy figure behind them paused uncertainly when it could no longer see them. It didn’t see Davie double back in the dark and grab it around the neck from behind.

“Dad!” Phillip cried out when Robert shone a torch onto the struggling figures.

“It’s not your dad,” Davie assured him. “He must have followed us from the house.”

The creature that looked like Marcus Freeman was putting up a fight, which only proved he wasn’t a Tiboran Mountain Steward at all. Davie could easily have overpowered an ordinary man in a fight like this. He was still over-powering the creature, but it took longer than it should before he grappled it to the ground. Even then, with the body oscillating between the copy of Marcus Freeman and its true form, it fought on. Davie screamed when an alien arm struck out and a fleshy hand pressed against his face. He fell back, and the creature almost had him at his mercy. Through stinging, watering eyes, Davie saw Phillip smash a large rock against the back of the creature’s head. Robert grabbed him in his arms as he stepped back, dropping the rock and trembling with shock.

“I killed it,” he said. “I... It... it...”

“You did what you had to do, boy,” Robert told him. “Think nothing more of it. Davie, are you all right?”

Davie couldn’t answer him, yet. There was an ugly red mark across his left cheek and the eye was swollen closed. He pulled himself to his knees and took several deep breaths. The venom was easily cast out of his body and the swelling subsided, but his face still felt numb and the redness remained. His eye still watered, too.

“The thing...” Phillip said. “It’s... melting.”

Davie tried to focus his eyes on the creature, but it was already formless. A few seconds later it was gone altogether, the deconstructed cells melting into the ground.

“It was a Zygon,” he said. “The venomous barb in the palm confirms it. We know what we’re dealing with, now.”

“What about my dad?” Phillip asked. “If the copy is dead...”

“We need to get on,” Davie replied. “Let’s not waste any more time.”

They walked on, moving carefully but quickly through the forest. Phillip still led the way. The boy was shaken by what had happened, though. Davie drew level with him and touched him on the arm.

“Don’t let what happened hurt you inside,” he said. “I was nearly eighteen when I fired on a ship full of Sontarans. It was something I had to do. I don’t regret it. It isn’t something I’m proud of, either. But I don’t lose any sleep over it. You’re much younger than I was, and I’m sorry you had to do that, even though you probably saved my life. Don’t make it the first notch on your gun, but don’t get hung up on regrets, either. And don’t let it change you. You’re still a kid with a lot of growing up to do. Don’t let this spoil one moment of it.”

Phillip seemed reassured by his words. Robert matched his grandson’s steps as they kept on moving.

“I had the same thought, myself. The first time I put my pitchfork through the heart of a Roboman... we both know that’s a merciful end for one of them... but it still felt like murder. And I wasn’t a wean like him. You said the right thing to him.”

“I hope so. I felt twice my real age saying it. As if I’d been fighting for a lifetime.”

Robert was going to say something else to him when Phillip gave a sharp cry. Davie was at his side at once, cautiously pointing his sonic screwdriver in laser mode at the path ahead. There was somebody, or something, there, something breathing heavily and painfully.

“Dad!” Phillip cried as the man stumbled towards them. Davie reached him first, pocketing the sonic screwdriver.

“It’s all right,” he told him. “We’ve got you. You’re safe. Mr Freeman... Marcus... Do you know me?”

“My Lord!” Marcus Freeman said.

“No, just your son-in-law. Take a deep breath. Steady yourself. You’ll be all right.”

Mr Freeman leaned heavily on his shoulder. He was almost fainting from shock, and that was no indication of unmanliness if Davie’s guess about what had happened to him was correct.

“Is it him?” Phillip asked. “Is it really dad, this time?”

“It is,” Davie assured him. “Come on, give him a hug. I think that’s his best medicine, right now.”

He stood back as the father and son embraced. He gave them a minute together. Then he knew he had to ask Marcus some serious questions.

“What do you remember?” he asked him.

“These creatures... orange fleshy skin... suckers... stinging... we were overpowered. I remember being carried... put into a... a sort of tank. The others are still there. I couldn’t wake them. It’s a sort of ship...”

“Definitely Zygon,” Davie confirmed.

“You’ve fought them before?” Robert asked.

“No, but The Doctor has. And anything he’s defeated, I know I can. Marcus, it’s a lot to ask when you’ve escaped from them, but will you come back with us?”

“I have to,” he answered. “Jake and Curt... I saw them in the cells next to mine. There were others, too. At least thirty occupied cells.”

“That’s why I need you to show me,” Davie said. “You got past the Zygons. Show us how you got out, then I can get in and rescue the others.”

Marcus clung to his son’s hand as they both led the way to the place where the forest was split by a rushing brook tfed by meltwaters at the snowline near the top of the mountain. The Crystal Falls was a rather spectacular waterfall where a solid rockface remained after the water had worn down the softer soil. It would be a beautiful place for a picnic, Davie noted. He would be happy to bring Brenda and the children there in the future.

But right now there was something far more sinister than forces of nature to contend with. He found the disturbed ground where something huge had landed, but there was no immediate sign of the ship. That didn’t surprise him. The stealth ship hadn’t remained on the surface. It had burrowed down into the soil. He swept about with the sonic screwdriver in sensor mode and found the entrance to the semi-organic Zygon ship. It was almost indistinguishable from the dark, leaf-litter strewn ground. Only when he used the sonic against it did a panel slide back to reveal a tunnel.

“It opened more easily from the other side.” Marcus Freeman confirmed.

“No guards,” Robert noted. “The Daleks always had patrols outside their base.”

“I don’t think there are many of them in the ship,” Marcus said. “I only came across two guards. One by the cells and one down there at the door. I... I killed them both. They took us by surprise when we came into the woods, but when I escaped from the cell, I surprised them.” Marcus showed a serrated edged hunting knife that was in a pouch on his belt. There was dried blood on it. “They took my gun, but they missed that. They’re as vulnerable as us when you cut them.”

“Keep that handy,” Davie told him. He wasn’t at all surprised by the calm way Marcus described killing the two guards. He was used to shooting predatory animals to preserve livestock. To him, the Zygons were a threat to far more than the livelihood of his family and friends. They were a threat to their whole existence. He did what was necessary.

“There’s a ladder,” Marcus Freeman continued as Davie looked cautiously into the dark hole behind the door. There was a glow of some kind of phosphorous light far below. “It goes a long way down. I thought I was never going to get out. At the bottom... there’s a corridor. The... whatever you called them... there’s about a dozen of them... in a sort of control room... And there’s another place... a sort of... I think it’s a hatchery... there were a lot of slimy things... smaller, pale... stubby... but like the bigger ones...”

“A hatchery on an exploratory ship?” Davie was puzzled by that. But it wasn’t his problem right now. The missing men were. “Come on, quickly. Show me where the prisoners are.”

Marcus Freeman shivered at the thought of going back down there, but he didn’t back away. He followed Davie down the ladder. Phillip followed him, then Robert. Davie reckoned it was about fifty feet deep. He could sense the soil and rock above him as he stood on the floor at the bottom. He could also sense the peculiar organic nature of the ship. It had the same smell as the Zygons themselves, except less earthy and more metallic. Organic metal, grown, not made.

“The ship buried itself and then sent out this conduit, burrowing through the Earth like a root, to make a way out to the surface. Clever. If they weren’t such a hostile race, bent on conquering and suppressing others, I might admire them. This organic technology is remarkable.”

As it was, they repulsed him. They took innocent people and hurt them and their families for their own ends. That made them his enemy, and his mission to defeat them.

To destroy them if he had to, if there was no other way.

“The prisoners are this way,” Marcus said. He took the lead. Davie kept Phillip by his side. Robert brought up the rear again. They moved quickly through the semi-organic corridors of a ship that was utterly alien, utterly unlike anything that Human, Time Lord or Tiboran considered familiar. The walls were ribbed and curved over without any obvious corners. The light came from within the walls themselves. Davie tried to stop thinking of it as organic, because the next step was to think of it as the internal organs of some great beast.

“Quiet, here,” Marcus warned. “This is where their command centre is.”

There was a window looking into the command centre. It also had an organic look to it, as if it was a transparent membrane, not glass. The creatures inside were busy at the huge computer banks. He wondered what they were doing, since the ship was clearly not flying. But he didn’t have time to find out right now.

There was another window further along the corridor. This looked onto the other place Marcus had mentioned, the hatchery, crèche, whatever it was. Inside were at least fifty small, pale, stubby limbed, infant Zygons. Their skin was slimy. They crawled aimlessly around the crowded room.

“This way,” Marcus said again. There was a bulkhead door, another organic looking one that opened when Davie applied his sonic screwdriver to the mechanism. Beyond the door was a long corridor with narrow cells either side. They all had panels of the organic glass.

Between them and the cells was a Zygon guard who blinked as if it was surprised to see a group of humanoids in front of it. Before the surprise wore off, Davie sprang forward. He punched the Zygon square in its squashed, fleshy face. It fell back against one of the cells, its head smashing through the glass, which lacerated the thick, rubbery but nonetheless vulnerable flesh around the neck. When the arterial blood stopped spurting the body disintegrated.

The cell the Zygon guard fell into was empty. But behind many of the panels were people. Phillip named some of them with an anguished voice. Others were strangers, some dressed in rural Tiboran clothes, one group wearing combat uniforms. Marcus confirmed that there was a company of Northern Tiboran Rangers on manoeuvres in the forest. They, too, had fallen victim to a Zygon surprise attack.

“Get them out,” Davie said. He aimed the sonic screwdriver at the lock on the first occupied cell. It clicked open. He aimed the sonic again, and used a wide ranging electronic pulse to open all the cells. “Once we get them out, the copies will be cut off from their brain patterns. They’ll start to disintegrate.”

“That’s going to scare a lot of people,” Robert observed. “Husbands... fathers... disintegrating in front of them...”

“Can’t be helped. We have to get them out of here. That lot in the control centre will figure out there’s a problem down here. Get them out and get them moving.”

The imprisoned men were dazed at first, but they quickly gathered their wits.

“Not that way,” one of the soldiers said when Davie tried to lead them back the way he came. “I was dazed from the gas they used on us, but I tried to remember where we were being taken. I remember coming in through that tunnel, over there. It opens out by the lake, only twenty yards from our camp.”

“Of course,” Davie said. “There would have to be access to the lake. Go on, everybody go that way. You men keep your service knives handy in case of more guards. Protect the civilians.”

The soldiers looked at him and recognised in his youthful face an authority not to be disputed. The company leader organised his men into forward and rearguard sections with the civilians between them.

“What about you, sir?” the commander asked.

“I need to do something here, first. Go on, get everyone out and then get to the high ground above the lake. I’ll be there as fast as I can.”

“Davie...” As the soldiers organised the retreat, Robert turned to Marcus Freeman and asked him for his knife. He handed it over. “I watched your back with the Daleks. I’ll do the same here.”

Davie hesitated. He wanted everyone else safe before he did what he intended to do.

“We’re family. We stick together,” Robert reminded him.

“I don’t have time to argue,” Davie conceded. And, in truth, after the others had gone down the tunnel, he was glad of his grandfather’s company. He had too often been alone on a hostile ship. It had happened too many times when he fought the Dominators. It was a comfort to have an ally at his side.

“What I want to do...” he said as he accessed a control panel and began something complicated that resulted in binary data scrolling down a screen at eye-watering speed. “It’s much the same as I did with the Dalek ship. Only... this time... I think I have to give them a chance... I can’t just...”

“Why the qualms this time?” Robert asked him. “You didn’t even blink about killing the Daleks.”

“The reason they’re here... I can read binary... it’s all there... the plan... They’re not just an exploratory ship. They’re colonising. The plan was to take over this planet, little by little, using their metamorphising ability to infiltrate the community. The adults... like the one posing as Marcus... the next step was to take the children... replace them with their own young... the hatchlings we saw. Eventually, when they had spread far enough they wouldn’t have to pretend to be Tiborans. They could shed their disguises, kill the hosts...”

“That’s monstrous,” Robert growled. “You can’t let them...”

“I don’t intend to. But... the hatchlings... as repulsive as they are... they’re children... When I think of what I intend to do to this ship... to them... I keep thinking of Brenda and my own babies... and... And I’m going to give them a chance. Just one chance.”

He finished what he was doing and then pressed a final button. He spoke into a speaker grille in the wall, and his voice was heard all around. He had accessed the communications system for the whole ship.

“I am Davõreenchrístõdiam?ndh?rtmallõupdracœfiredelunmiancuimhnemilágrodánte de Lœngbærrow-Campbell, Time Lord of Gallifrey and Earth. I have sabotaged your ship by routing a conduit from the engine room to the heart of the mountain you landed next to. If you check your environmental controls you will note that it is a currently dormant volcano with a fair amount of magma left down in the caldera. You have fifteen minutes, standard universal time to get into orbit before the conduit breaks through to the magma. I know Zygons don’t like fire. That’s in the list of fun facts about your race that I inherited from my granddad. You’ll like lava flowing through your ship even less. You won’t be able to stop it, no matter what you do. I’m a much smarter computer programmer than any of you. Your only option is to initiate a take off sequence. That takes a full ten minutes according to your engine specifications. That’s a margin of five minutes, so don’t spend any time debating the issue.”

He turned and nodded to Robert.

“Run.”

They ran down the corridor that led to the lake. It was long. Davie started to worry if he had given them enough of a margin. They were only part way when he heard a rasping noise behind them. There was at least one Zygon in pursuit and he didn’t have time to fight them. He grasped his grandfather’s hand and folded time until he felt cooler air ahead and they burst out onto the muddy edge of the lake.

“Not much time,” he said, checking his watch. “We need to get higher.”

They climbed up the steep bank to the edge of the forest. Phillip broke from the trees and started to run towards them before one of the soldiers pulled him to the ground. Davie and Robert ducked as they saw two more men in khaki break cover either side of them. They heard two rifle shots ring out in the night. He turned briefly and saw two Zygons fall near the tunnel entrance.

“Good work,” he said as the soldiers closed in giving him and Robert cover as they reached the higher ground. He was impressed by how much they had done while he was inside the Zygon ship, making the civilians safe in their camp and taking up defensive positions.

“They’ve passed the ten minute mark,” Davie noted as Phillip hugged him and Marcus congratulated him on a job well done. “They’re cutting it fine.”

“Who are?” Phillip asked. “Everyone’s here. You saved them all.”

Davie didn’t answer. He looked towards the trees, expecting the ship to take off loudly as it burst up through the ground and accelerated into the sky. It didn’t. Then he heard a shout and turned to see an eerie orange glow at the mouth of the tunnel they escaped through. Lava was pouring out. It hit the ice cold lake and rapidly cooled. It would keep on coming for a few hours, but eventually form a plug blocking the flow through the tunnel.

“They didn’t take off,” Davie said. He shuddered as he imagined the lava breaking into the command centre engulfing the Zygons. He thought of the hatchlings squealing as they burnt to death. “I gave them the chance. Why didn’t they take it?”

“Perhaps they thought you were bluffing?” Robert suggested.

“Perhaps there was something wrong with their ship and they couldn’t...” Davie added. “In which case... I murdered them.”

“No,” Robert assured him. “You fought back against an enemy that meant to cause untold harm to innocents like young Phillip, there. Don’t you have one single regret about it. Not one. You did right, Davie. You can go home to your wife and look forward to the birth of your own weans with a clear conscience.”

Marcus Freeman heard what he said and added his own voice to the assurances.

“My son’s life would have been taken for one of those vile creatures. I thank you for stopping them.”

Davie felt reassured, but he knew this wasn’t a victory he would celebrate as some of the released victims were celebrating. He felt no reason to cheer.

“Let’s get everyone back where they belong,” he said.

As Phillip had predicted, there were homes where Zygon copies had disintegrated, leaving confused and grieving families. The return of their real loved ones eased the grief, but they would all need time to get over the shock. For the Freeman family, at least, they had the trip to Earth as a respite.

“There’s something I need to show you before we leave,” Davie said to Marcus Freeman before breakfast the next morning. “It won’t take long.”

He brought him to the TARDIS and put it into hover mode over the lake before going down underneath like a submarine. Davie watched the monitor carefully as the TARDIS moved along the lake bottom.

“There,” he said when the creature he was looking for appeared on the wall-mounted viewscreen.

“What is it?” Marcus asked. “It looks like...”

“It’s a Skarasen,” Davie replied. “An aquatic creature from Zygor, the home planet of the Zygons. I knew there would be one. The Zygons milk their lactic fluid for nourishment on long space voyages. They chose this location because they could release it into the lake to feed itself. This isn’t a fully mature one. It’s only about nine foot. An adult is more like fifty foot.”

“We have to get it out of the lake, then!” Marcus exclaimed.

“No,” Davie told him. “Leave it there. Make sure fish stocks are maintained, so that it isn’t tempted to move onto the land and eat sheep and cattle or pet dogs. You have two choices. Either keep it secret, and do what you must to stop anyone finding out about it. Or... let it be known that it’s there... and you could have one hell of a tourist industry, winter and summer, and all kinds of grants coming your way to conserve a unique species.”

“Could that work?” Marcus asked as he stared at the long necked amphibious creature, noting how many teeth it had.

“She’ll be safe enough down there until you get back from your visit to Earth,” Davie pointed out. “It’s winter and she’ll stay in the deep water in torpid state. Time enough to think about how to handle it. I’ll even take you up to Loch Ness to see her cousin, before you decide.”