The TARDIS materialised next to the souvenir kiosk in the main hall of the Victorian Gothic National History Museum in London, England, Earth, in March of the year 2012.

Tegan and Turlough were not impressed. The London Olympics that The Doctor had promised to take them to wouldn’t start until July.

“This is just a temporary stop,” The Doctor promised. “There’s something I have to check out, urgently.” He stepped out of the TARDIS and looked up at the high glass roof that let in natural light to the huge hall. It wasn’t letting in a lot of it right now. It was a dull, grey sky above and rain beat a tattoo on the roof.

Apart from the sound of the rain it was quiet and still in the hall, famously graced by a complete diplodocus skeleton that would usually be surrounded by awe-struck school-children.

“Seven o’clock,” The Doctor said, checking his wristwatch. “They’re not open yet. That’s all right. I’m a Fellow of the Natural History Society. I’m allowed in any time.”

He fished in his pocket, giving Turlough a large ball of string, a cricket ball and an assortment of alien coinage to hold onto before finding a beautifully printed cream coloured card edged in gold-brown. Turlough read it.

“You were a fellow of the society in the 1870s. This place was built in 1881 – according to that information sign over there.”

“Yes, I advised them on their first exhibition,” The Doctor said with no trace of modesty, false or otherwise.

“That might not cut much ice in 2012, Doc,” Tegan pointed out. “Maybe we should wait for opening time.”

She thought her point was well made when, ten seconds later, a man in security officer uniform called out from the landing where the marble statue of Charles Darwin sat mutely in his chair. The guard hurried down the stairs and approached them cautiously, his hand on his radio transmitter to summon help.

“It’s all right,” The Doctor told him calmly. “I’m The Doctor.”

“You are?” The guard looked relieved. “You’d better come this way. Nobody’s touched the body, yet.”

“Body?” Tegan and Turlough looked at each other and then followed The Doctor up the stairs, passing to the left by Mr Darwin and up another flight, then through a door, a long, echoing corridor and two more doors before they reached yet another door guarded by a uniformed policeman.

The body was on the floor of a glass-enclosed ‘clean-room’ within a larger laboratory. An early morning cleaner and two people still wearing their outdoor coats waited anxiously along with two more uniformed policemen. They all moved aside as The Doctor slipped on a white coat and a face mask that were hanging on a peg and then stepped into the airlock. Tegan watched him open the inner door and carefully approach the body then she pulled a notebook and pen from her pocket and turned to the eyewitnesses. They were all in too much shock to question her right to ask questions. She established that the cleaner had discovered the body just before the other two people, Professor Karen Smythe and Doctor Ian Sanderson, arrived at the start of their shift.

“It’s Gregory Orpington,” Professor Smythe said, choking back a sob. “Doctor Orpington. He’s a… I mean he WAS…. a mineralogist. He was working on one of our newest acquisitions in there.”

“It can’t be murder,” Doctor Sanderson said. “The clean room was locked from the inside, and there’s no sign of a struggle in there. Besides, the laboratories need key-code access.”

“It wasn’t murder,” Karen Smythe insisted. “But look at him. Look at his face. He looks as if….”

She couldn’t explain what Doctor Orpington’s face looked like. Tegan looked through the glass wall of the clean room and thought he looked like he was made of the same white marble that Charles Darwin on the stairs was carved from. His face and the exposed part of his arms were unnaturally pale and there was a sheen to his skin that was utterly unnatural even to a dead body.

“It must have been some kind of accident,” Turlough said, trying to sound calming and reassuring.

“Don’t worry,” Tegan added. “The Doctor will find out what happened.”

“If the press find out about this, there will be all kinds of speculation,” Karen Smythe added. “Greg was working on the Tissint Meteorite….” Turlough and Tegan both looked blank. “The Mars Rock,” she added.

“I… see,” Tegan said, even though she didn’t. She looked around. The Doctor was coming back out of the airlock. He left the lab coat and mask inside before stepping out.

“The museum must be closed today,” he said. “Nobody comes into this building without clearance. Get me a phone. I need to call U.N.I.T.”

“Call who?” One of the policemen spoke up for the first time since The Doctor’s arrival. His self-assured and hypnotic manner that pervaded everyone in the room when he walked in had worn thin by now. The officer was trying to assert his own authority….

…..Unsuccessfully.

“The United Nations Intelligence Taskforce,” The Doctor explained as he accepted the cordless telephone from Karen Smythe’s desk and tapped a long number on it quickly and without hesitation. “They’ll be taking over here. This is their purview.”

“What is?” Doctor Sanderson asked.

“Dead Human beings whose bodies have been infected by alien organisms,” The Doctor answered. “Fortunately the contagion is contained within the clean room. You should all have been perfectly safe out here. Just to be on the safe side, the U.N.I.T. people will want to make sure you go through a decontamination process.” He turned away from the astonished scientists as his call was connected at the other end. He gave a long alpha-numeric code and a few moments after that he was clearly connected to somebody with very high authority. It didn’t take very long to arrange for a military lockdown of the Natural History Museum and the removal of the body under careful conditions to an enclosed crematorium for immediate disposal.

“I’ll leave it in your capable hands, Captain Magambo,” he said at last. “I will be heading straight for the crater site. It would save a lot of time and misunderstanding if the north African section of U.N.I.T. knew I was coming. Tell them I’ll be arriving in twenty-four hours. That will give them time to get set up.”

With that he turned and walked out of the laboratory leaving everyone there thoroughly startled by the turn of events, including Tegan and Turlough who had to run to catch up with him.

“What killed that man?” Tegan asked as they hurried past Charles Darwin again, their footsteps on the stairs echoing in the silent hall. “Did you really mean that… about an alien organism?”

“Would I say that if I didn’t mean it?” The Doctor asked. “His body was riddled with the infection. That’s why he looked the way he did.”

“Like he’d been turned to stone?” Tegan queried. “We all saw him. His face….”

“Turned to ice,” The Doctor answered. “His blood was, anyway. The organisms killed off the red and white cells and the platelets and turned the plasma to ice. His veins were full of frozen water – Martian water, technically.”

“Martian?” Turlough echoed. “That’s what the lady Professor said. The something or other meteor – Mars Rock….”

“Tissint Meteor,” Tegan added. “That’s what she said. “But I have no idea what that means.”

“Tissint is a village near the place where the most recent meteor of Martian origin fell to Earth,” The Doctor replied at the TARDIS door. “It’s why we’re going to North Africa. Dress for a dry, hot climate, children.”

The Doctor, of course, dressed exactly the same as he always did in that cricket themed outfit that somehow managed to fit into almost any time and place without comment. The staff of the Natural History Museum had accepted without question that he was a medical doctor qualified to go into the cleanroom and examine the body. When the TARDIS landed in an army camp hastily set up in the dry, hot landscape just north of the border between Morocco and Algeria he was greeted by a U.N.I.T. lieutenant in desert combats and kevlar helmet instead of the all too distinctive red beret.

The lieutenant saluted The Doctor neatly and shook hands with his companions before offering to escort his party to the colonel in charge of Operation Desert Calm.

“Desert Calm?” Tegan queried as she, dressed in loose cotton shirt and pants and a wide-brimmed hat, did her best to match The Doctor’s pace. Turlough, beside her, had completed his desert ensemble with a white cotton keffiyeh that brought out the blue in his eyes and made him look like a cross between Rudolph Valentino and Peter O’Toole in Lawrence of Arabia.

“Just a military thing,” The Doctor said in response to Tegan’s question. “Let’s hope it isn’t the Calm before the Storm or they’ll be stuck for a codeword.”

The colonel in charge was set up in a large tent that was cooled by two rather noisy fans just inside the entrance. He had somehow managed to transport a mahogany desk and a sideboard with crystal decanter and glasses set out on it to the desert in the very short time they had been given to set up Operation Desert Calm. Tegan tried not to laugh out loud at his old-fashioned handlebar moustache and the clipped English accent that seemed too precise to be true. She thought fondly of Brigadier Lethbridge Stewart who she had met once. He must be retired now, of course, if he was still alive. And this man, identified by a nameplate on his desk as Colonel Geoffrey Howard-St. John-Smythe was his replacement.

She hoped he was up to the job.

The Colonel accepted the lieutenant’s salute and dismissed him. He gallantly offered a chair to Tegan first and then Turlough and The Doctor before getting down to business.

“We’ve been on site for twenty-four hours,” he said. “Ever since your instruction to contain the area. We haven’t found anything on the surface around the craters, but our scientific advisor is getting ready to lead an expedition into some caves close by where we detected unusual minerals.”

“Caves?” The Doctor queried. He glanced at a map pinned to a board beside the desk. There was a long high ridge that cut through the landscape. Beside the map were photographs of the area. They reminded The Doctor of somewhere else entirely.

Actually the dry sandy plateau and the iron coloured rocks reminded him of two very different places with very different emotional responses. He was reminded first of the Red Desert of Gallifrey where, as a young man impatient for adventure, he had taken part in extreme sports like high-speed hovertrike racing and free-climbing without the help of anti-grav cushions. That was a good emotion, tinged with a little homesickness and nostalgia.

The terrain also reminded him very forcefully of the home of the Ice Warriors on the Red Planet – Mars. They were reptilian humanoids, cold blooded. They were not really the ideal species to have evolved on a world so far from the sun as Mars, and they tended to keep to the caves beneath the surface where the rocks were thermally heated from the molten core of the planet. When they emerged onto the surface they wore body armour that not only made them look fearsome but acted as insulation for their bodies.

The caves of southern Morocco would invoke the same feelings of nostalgia in the Ice Warriors if they saw them. They would be right at home there.

But it was pure coincidence. The Tissint meteor was a piece of the Martian bedrock that was ejected into space when an asteroid or comet smashed into the surface an estimated 60,000 Earth years ago. The Ice Warriors hadn’t evolved their highly sophisticated if militaristic society then, and the proto-Warriors of that time had no designs on planet Earth. Whatever he suspected was happening had nothing to do with them.

“Doctor, are you listening?” Tegan asked, breaking into his musing. He hadn’t been. He literally WAS miles away – millions of miles away – in his thoughts. “The Colonel just said that there are a number of people missing from the local towns – Tissint and Tata. He dismissed it as a matter for the local authorities but….”

“It could be connected,” The Doctor said. “Nobody should go into those caves without full hazmat protection. I assume you have such equipment available? I have some in the TARDIS for us.”

“Yes, if you think it necessary,” The Colonel answered. “Ah, here’s our scientific advisor, Doctor Taylor.”

The light from outside the tent was temporarily blocked by a figure that might, at first glance, be mistaken for an alien being. From the ground up there was a pair of combat boots with grey socks pulled up over the ankles. A pair of knobbly knees were exposed above those before baggy combat fabric shorts. Further up was a very loose desert cam coloured shirt and a combat jacket that must have been at least three sizes too big across the pigeon chest of the short figure. He topped the outfit off with a keffiyeh – or possibly a tea towel from the mess tent. Either way it was improperly fastened and would have fallen off his head if it was not held on by a huge pair of protective goggles that must have had prescription lenses as they had the effect of enlarging the wide open eyes within.

“You don’t have to salute me, Doctor Taylor,” the Colonel told him as the apparition’s hand went to his temple. “You’re a civilian. You don’t have to salute The Doctor, either. He’s also a civilian. I don’t know if you have met….”

“Indeed I have,” Doctor Malcolm Taylor replied in an excited voice. He pushed up the goggles and his keffiyeh became even more ludicrously skewed. “Although not in this stage of his personal timeline. Doctor, you don’t know me, yet… but we’re going to have some marvellous adventures in your future. And might I say it was… is… will be… an honour to work with you.”

“Doctor Taylor is a very clever scientist,” the Colonel said, obviously feeling it needed to be stated in case he was mistaken for a member of a comedy concert party sent to keep up troop morale. “Doctor Taylor, why don’t you show The Doctor your findings, so far.”

“Yes, of course,” Doctor Taylor pulled a strange looking gadget from the pocket of his shorts. It looked like a very large television remote control but it opened out into three separate panels, one of which was an LCD screen. “As you can see, Doctor, there is a large concentration of elemental and isotopic compositions consistent with the Tissint meteor within this ridge south of the crater field. This suggests that material originating on Mars has been moved into the caves, but I won’t know if that is correct until I take an expedition inside. These figures may, in fact, be wrong. If there really is such a large concentration of these isotopic readings then the meteorite would have to have been exponentially larger than the fragments so far identified. There is also the question of how they got into the caves when the meteorite landing was observed by scientists on the scene in July 2011 and all material at the site recovered within twenty-four hours.”

“Yes, both those questions occurred to me, too,” The Doctor answered him. “And you are quite right. An expedition into the caves is the only way to find out. Colonel, I’ll need a small group of your men, no more than a dozen. Turlough, you come, too. Tegan, you can help Doctor Taylor collate his findings here at camp….”

For several minutes the tent echoed with two voices raised in protest about that idea, the loudest by a very small margin being Tegan who called The Doctor a male chauvinist and insisted that she was far more experienced than Turlough when it came to roughing it in strange places. It was only because she was a woman….

“All right, Tegan, you come as well. But Doctor Taylor, really, I need you in your laboratory doing what you do best – scientific research.”

Malcolm was disappointed, but he turned away to do as The Doctor asked. Tegan and Turlough waited while The Doctor compared the schematic on Malcolm’s gismo with the printed map on the wall and then turned to them with the sort of expression Sherlock Holmes invariably had when he told Watson that the ‘game was afoot’.

The Doctor and his companions travelled to the foot of the ridge in the TARDIS in hover mode. The soldiers went in the back of a desert camouflaged six-wheeled all-terrain Pinzgauer 716 which, despite being designed for just this sort of rugged territory bounced around erratically and made Tegan feel quite glad to be in the old TARDIS despite many a bumpy ride in her. The Doctor kept a close eye on those readings on Malcolm Taylor’s hand-made gismo as they approached the cave entrances. He couldn’t fault the eccentric scientist’s work.

The soldiers were already organised into a guard outside the caves and a fully armed team that would accompany The Doctor inside. He ordered his companions into garishly orange hazmat suits before they exited the TARDIS. Even he, on this occasion, put on the all-covering suit, boots and helmet. Tegan and Turlough disliked the claustrophobic suits but they remembered the man in the Natural History Museum who had been working on one very small piece of the Tissant Rock. They weren’t going to take any chances, even if the three of them looked like rainproof orange Wombles.

The Doctor smiled at Tegan’s Womble reference. It was preferable to his own thought. The soldiers were in army green NBC suits that would protect them from almost any environmental danger. With their faces behind thick glass visors they looked rather like the Ice Warriors he had been thinking of earlier.

He led the odd looking party into the larger of the cave entrances. Malcolm’s gismo proved useful in another way, identifying the cracks between strata that could be used as tunnels.

“I’ve seen cave systems like this,” Tegan said. “The Capricorn Caves in Rockhampton…. They were my favourite school tour. They were formed by water running through the rocks over thousands of years. We have plenty of water in Queensland. Too much in the rainy season. But this place is so dry it gives new meaning to the word.”

“There was water here, once,” The Doctor answered. “These rocks are millions of years old. When they were new the continent of Africa lay much further south of the equator than it does in your time. There was a wetter climate than Morocco has now. Water erosion formed these cave systems long before the Tissint meteor was thrown into space and set off on its 60,000 year journey to Earth. That’s rather an amazing thought, isn’t it? The patient action of nature building caves and sending meteorites through space. Doesn’t it give you a humble perspective of your place in this wonderful universe of ours?”

“Just a bit,” Tegan agreed.

“Doctor, should it be cold down here?” Turlough asked. He showed him the temperature gauge on the wrist of his hazmat suit. “Granted the sun has never peeped down these holes since the Earth cooled, but surely it shouldn’t be THIS cold?”

It was zero degrees centigrade, dropping to minus zero as he spoke. Inside the hazmat suits it was something like the temperature of a cool oven just from their own body heat, so they were not suffering from the cold but it was an important detail about their environment, nonetheless.

“No, it shouldn’t be as cold as that,” The Doctor admitted as the gauge reached minus one. “But I’m not altogether surprised if this is what I think it is down here.”

“What do you think it is, Doctor?” Turlough asked.

“I hope I’m wrong,” The Doctor added. “Because one man has already died in London and there could be many more if I’m right. I really don’t want to be right. But the falling temperature makes it all the more certain that I am….”

“Doctor, you’re rambling a bit there,” Tegan pointed out. “WHAT is it that you think we’re going to find?”

“This for a start,” The Doctor answered. Since they entered the cave system they had been relying on powerful army issue torches to see by, but as the temperature dropped another two degrees below zero they began to realise that they didn’t need them. The soldiers switched off their torches and they could all still see clearly.

“How come?” Tegan asked. It was an obvious question but she was the first one to ask it.

“It’s the walls,” Turlough answered. “They’re covered in something… I think its frost. Frost with a source of light within it.”

He started to reach out to touch it then changed his mind. He remembered the man in the Natural History Museum.

“Phosphorescent bacteria within the ice particles,” The Doctor confirmed. “Don’t touch it.”

That last warning wasn’t necessary. Everyone tried to avoid contact with the wall, even through their protective suits.

“Ice is formed from water,” Tegan pointed out. “I thought we established there is no water down here and hasn’t been for millennia.”

“This water isn’t natural,” The Doctor answered. “It’s not even entirely from Earth.” He turned to the soldiers who had accompanied them. “I don’t usually approve of guns, and I have firmly held principles about preserving life at all costs. But when you see… what I know we’re going to see very soon… don’t hesitate. Aim for the head. Believe me, you’ll be doing them a favour.”

The sound of semi-automatic rifles being set to single shot for the precision firing The Doctor had called for echoed around the tunnel loudly. Tegan shivered. She didn’t like guns any more than The Doctor did, and what he had just said to the soldiers was disturbing. Just WHAT was he expecting to see?

Less than a dozen yards ahead the narrow tunnel formed by the erosive action of rivulets of water over thousands upon thousands of years opened out into a cavern formed by the same actions of water seeking the lowest point through the lines of least resistance. It was not the biggest cavern any of the party had ever seen. It was by no means a match for the Capricorn Caves that Tegan had mentioned before, and Gallifrey had some amazing subterranean features. But as caverns went it was impressive.

What was especially impressive about it was that it was covered in ice – the floor was an ice rink. The walls and the high ceiling glittered with a thick layer of frost with the same phosphorescent properties they had already observed.

And it was occupied.

The first soldier to emerge from the tunnel where they had been forced to move single file did exactly what The Doctor told him to do. The syncopated sound of two rounds being fired in quick succession and the sharp ring of the cartridges ejecting onto the iron hard ground shocked Tegan, but not as much as the sight of a grey-faced man with blank eyes who fell backwards from the force of the two bullets hitting his forehead.

He was grey-faced because, unlike the white-skinned Doctor Orpington, he used to be a dark-skinned native Moroccan before his blood was turned to iced water. There were at least a dozen other grey-faced men in the cavern. They all had blank eyes even before the soldiers opened fire on them. They were moving in a slow, zombie-like way, carrying something about the size and shape of a punctured football or a balloon filled with water rather than air.

“Shoot them,” The Doctor ordered. “All of them. Don’t think of them as men. They ceased to be Human when their blood was infected. They’re just empty vessels now.”

The soldiers fired. For several minutes the cavern rang with the sound of gunfire. Then they stopped firing. All of the grey-skinned zombies lay still among heaps of the misshapen balloons.

“What are those things?” Tegan asked. “Those balls of… whatever?”

“Those would have destroyed planet Earth as we know it if they had been allowed to get out of this cavern,” The Doctor answered, bending to examine one carefully. “The bacteria came to Earth embedded in the Tissint rock. That’s all it was originally – just a bacteria. No sentient organism, just a bacteria. Out there in the baking desert it wasn’t even harmful. It needed a cool place to start the process of binary fission that makes it grow. I don’t know who was foolish enough to bring one of the fragments of rock into the caves. Doctor Taylor was correct when he said that the meteorite landing was observed and the pieces collected almost immediately. I wonder if some local thought he could make money out of them. He might have hidden a couple of pieces down here intending to collect them later and sell them on the black market.”

“Pieces of Mars rock,” Tegan noted. “Some people would pay a lot of money for that. Personally I’d be inclined to think it was a con. I mean, how would you KNOW it was from Mars?”

“In the case of this Mars rock you would know because it would kill you. The piece Doctor Orpington was examining back in London had been in the right conditions for the binary fission to begin, and he was infected. The thief, perhaps when he came back to collect his fragments, would have walked into a deadly trap. The fission would have been unchecked down here in the dark and the cold. He would have been killed. His bodily fluids would be the material needed to breed more bacteria.”

“And infect more people?” Turlough surmised. “But how come….”

The question he had started to ask went unanswered. Two of the grey-faced zombies tried to stand up again. Shots rang out and they fell down again, but three more were starting to rise up.

“All right,” The Doctor decided. “Everybody out of here. Sergeant, do you have incendiary grenades?”

“Yes, sir,” the sergeant answered.

“All right. Tegan, Turlough, you get going. I’ll be with you in a few minutes.” He turned to the soldiers. “When I give the signal, be ready to run. Nobody takes any chances with their lives.”

His two companions were reluctant to leave ahead of him, but he repeated his order and there was no argument to be made. The zombies kept on rising and the soldiers were shooting them down. Something drastic had to happen, and The Doctor’s solution was as drastic as they came.

They ran, along with one of the soldiers to watch their backs. As soon as they were out of sight The Doctor stepped into the cavern and looked around at the glistening walls. He closed his eyes and looked with his mind, feeling, listening, reaching out mentally to touch the strange things around him.

“Yes,” he said with a sadly resigned tone. “Yes, I thought as much. That’s why this has to be done.”

He stepped back into the tunnel and ordered the soldiers to throw the incendiaries into the cavern. They did so and then moved as quickly as possible down the narrow passage, the rearguard looking back to check that they weren’t being pursued. The red-orange glow from the inferno created within the cavern was visible for a while, but then they turned a corner in the twisting tunnel and they could only guess what was happening.

Emerging into the dry heat and the bright sunshine was disorientating. Everyone blinked and stumbled a little but there was a feeling of relief and a sense that they had ‘made it’.

“Can they get out?” Turlough asked. “What if some of them escaped?”

The Doctor looked at the cave entrance and bit his lip thoughtfully.

“Sergeant, we’ll need some high explosives – bring down the roof of that cave.”

The sergeant ordered that right away. They waited by the TARDIS for the ordnance to arrive and the charges to be set. Meanwhile, The Doctor explained what he had felt when he stood in the cavern.

“I was wrong about it being non-sentient,” he said. “The bacteria did have a kind of consciousness… something like a mind, with one pre-occupation – conquering this planet. It planned to do so by spreading out of the cave using the ice zombies it created. And, yes, my first guess about that was right. A local man hid the fragments in the caves where it was cool enough for the bacteria to grow. He became the first of many victims – the people missing from the town. When there were enough of them, and when there was enough bacteria to explode all over the outside despite the heat of the Moroccan day, there would be no stopping it. This inhospitable desert would quickly become an inhospitable ice field. Anyone going near it would be infected.”

“Ambitious bacteria,” Turlough commented.

“Very ambitious. Even so, it wasn’t personal. It wasn’t trying to destroy the Human race out of any hatred or vendetta. It simply used an organic lifeform for its own ends. It was Earth’s misfortune that it landed here.”

“But it’s over, now?” Tegan asked. “We killed it?”

“I killed it,” The Doctor said with a deep sigh. “I knew when I saw Orpington in London that it might come to that. I didn’t like doing it, but for the sake of this planet’s people, its flora and fauna, even its dry, inhospitable deserts, I didn’t have any choice.”

“You did ok. Doctor,” Turlough assured him. “We didn’t need to be with you, did we? All we did was tag along.”

“I’m glad you did,” he admitted. “Having friends who understand what I have to do made that hard choice a little easier.”

“We didn’t need Malcolm, either. He’ll be disappointed.”

“Yes.” The Doctor smiled softly. “I never really DID need his help, here or at the camp. But he looked the sort who would be a hindrance on a field trip. Never mind. I think I know a way of making it up to him.”

A Warthog all terrain vehicle rolled up on its tracks and stopped beside the Pinzgauer. The explosives experts poured out of the back along with their equipment and quickly set to work. A short, squat figure in an ill-fitting NBC suit stumbled out after them. Behind the visor the wide-open eyes rimmed by the prescription goggles were unmistakeable.

“Speak of the devil,” Turlough noted as Doctor Malcolm Taylor hurried over to them.

“The crisis is over,” The Doctor told him. “But come on. Pop aboard the TARDIS for a little trip.”

“A trip!” Malcolm almost tripped over his heavily booted feet in his eagerness. “A trip to where?” he asked.

“Mars,” The Doctor announced as the TARDIS materialised on the Red Planet’s wind-swept dusty surface. There really was a reddish tinge to the sky through the atmosphere of mostly carbon-dioxide. It was utterly alien to the Human eyes that viewed it, especially Malcolm who was beside himself with glee. “I thought you’d all like to see where the problem began. It’s not worth the trouble of putting on pressurised suits to go out there, especially after all the bother with the hazmats. But there it is. A dry, apparently lifeless desert.”

“Apparently?” Malcolm queried. “You mean it isn’t really lifeless?”

“As far as Earth in your century is concerned, it is,” The Doctor insisted. “The ice bacteria that caused us so much trouble are long gone from the surface. It is too dry for it, now. But deep below the surface of this planet are many secrets, some of them humans are never supposed to know about. Others you may well come to unlock in time, as your yen to explore and find out about the universe takes you out here. Just… be careful, all of you. I might not be able to look after you every time you get into trouble.”

“We’ll try, Doctor,” Malcolm promised. “We’ll try.”

“Yes,” The Doctor answered quietly. “Yes, you will.”