Sarah Jane slept peacefully in the comfortable hotel bedroom – at least for a little over two hours before something woke her.

She sat up and looked around, wondering exactly what it was that had disturbed her sleep.

Then she heard it again - a peculiar electronic sound coming from somewhere outside. She went to the window and looked out.

The conservatory was directly below her bedroom. She looked down on the glass roof but all seemed quite normal.

All the same, as a journalist, she had to go and look. She grabbed a dressing gown and slippers and quietly hurried downstairs. The French doors from the dining room to the conservatory were locked, but from the inside, and for fire safety the key was nearby.

As she unlocked and opened the door, she heard the noise again. She looked around the conservatory and was surprised how easily she found the source.

It was the pair of radios that the Freer boys had been playing with earlier. They must have been left on when the children abandoned them in favour of their tea and indoor activities before bed. Sarah Jane wondered if The Doctor had done something alien and clever to the batteries, too, since they probably ought to have worn down by now.

The overriding noise was like an industrial drill in the street, much as Mrs Atkinson had described. But there was something else, something Sarah Jane was sure was a voice. It was a rasping, inhuman voice, speaking as if English was not its natural language. She had trouble trying to make out anything meaningful from the few words she recognised in the gabble.

Until she heard the word ‘Ransome’ very clearly.

Aliens had kidnapped Professor Ransome. Despite the fact that he worked for U.N.I.T., an organisation that fought alien incursions on Earth, nobody, not even The Doctor, had considered THAT possibility.

But now it made perfect sense. There were aliens at work somewhere along this quiet coastline and they had taken the Professor to make him work for them.

She brought the pair of radios with her as she headed back upstairs. The Doctor had to see this right away.

She started to knock on his door when she noticed it was unlocked. She pushed it open and stepped in. A bedside lamp was switched on and the bed looked slept in but he was not there.

“Sarah Jane!” The loud whisper was from Mike Yates standing at the door in hastily thrown on jeans, tee shirt and plimsolls. “The Doctor is missing, too? The Brigadier isn’t in his room.”

“The aliens must have them,” Sarah Jane reasoned. She showed him the radios, now just emitting static, and told him the story. Mike readily agreed with her hypothesis.

“The Doctor said that these only have a range of two hundred yards,” he said, taking one of the radios from her and examining it carefully. As he did so it burst into life again, the excruciating sound accompanying alien voices speaking English clumsily.

“So the alien base is VERY near,” Sarah Jane reasoned again.

“Grab some warmer clothes and let’s go.”

She did that, rejoining Mike in the conservatory. They walked in the chilly pre-dawn, each holding onto one of the radios as they crossed the garden and stepped onto the single lane road that wound along the ragged coast.

“We can’t exactly triangulate the position of the transmitter,” Mike admitted as he turned left to right, holding up the radio. “But… yes… the sound is stronger this way.”

They were heading along the cliff past the coastguard lookout with one light on for the man on duty overnight, past the cottages where his colleagues and their families were all sleeping the sleep of the just. Sarah Jane spotted a light that had no such justification as the peculiar outline of the radar monument was silhouetted against the night sky.

“that’s the old chapel, isn’t it?” she commented. “I suppose somebody might be PRAYING?”

Neither she nor Mike were devout enough to imagine that as a likely possibility. They approached the chapel cautiously and knew they were right to do so when they saw the silhouette of what was undoubtedly an alien moving about within the sacred walls.

They crept even more quietly to the door and watched the being, fully seven foot tall, its general shape humanoid, but surely only in some kind of simulacrum. It looked as if it was made of glass or crystal – a living crystal that reflected the light off myriad facets. The skull faintly glowed a yellow-orange that put Sarah Jane in mind of a Belisha beacon.

It was busy stacking up strange polyhedron shaped containers along one wall of the chapel, as if it had been designated an alien warehouse. As they watched, another alien appeared from behind the altar delivering more of the boxes. There was a conversation in hissing, sibilant voices, between the two. They were speaking in their own language, but Sarah Jane understood the words because even here in Dorset, far from where The Doctor had left the TARDIS at U.N.I.T. headquarters, she, as a regular traveller in the time vortex, was still influenced by its translation circuits. She related to Mike that the first alien had told the other not to bring any more containers until he was ready for them.

“Why fill a Norman Chapel with boxes?” Sarah Jane asked in a low whisper.

“Good question,” Mike answered. “If I had to guess… I’d say that one was a quartermaster and those are supplies being made ready for despatch. But where they’re coming from, I don’t know.”

“Let’s find out.”

Mike hadn’t really expected what Sarah Jane did next. If he had, he might have stopped her. As it was, he barely had time to suppress an exclamation of surprise when she bolted forward, grabbing the heavy metal flower vase on the side table and smashing it against the back of the alien’s head.

Smash was the operative word. The crystal skull shattered like the glass in a car windscreen, the crazing radiating out from the point of impact. The alien collapsed in a forlorn heap, the glow slowly dying.

“I think I killed it!”

“It… looks like it,” Mike answered. He was a soldier. He was trained to kill. He HAD killed when a desperate situation called for it, but even he was shocked by the effect Sarah Jane’s relatively mild action had produced.

“It can’t be helped,” he reasoned. “You didn’t know. Besides, they ARE aliens, doing something they shouldn’t be doing. It’s not your fault.”

Sarah Jane wasn’t completely placated by that. She was sure The Doctor would have taken a different view. But there was nothing she could do about it, now. She put down the vase and slowly turned to where Mike was examining a gap in the flagstones behind the altar.

“There’s a tunnel down here,” he said. “Come on.”

Of course, Mike had remembered to bring a torch. He still thought like a soldier, and a soldier would know that walking around dark places was a likely scenario. He led the way down the old stone steps.

“They ARE old,” Sarah Jane noted. “Could this be some kind of priest hole from the sixteenth century, when they banned the sort of Masses that the chapel was built for?”

“On this coast, more like seventeenth or eighteenth century smuggler’s steps,” Mike answered. “I’ll BET any money this leads to the sea – some quiet cove with calm waters for bringing in boats.”

Mike was wrong. It was entirely possible there was a sea opening somewhere further along, but the tunnel was running parallel to the sea rather than directly to it. He estimated that they had walked at least a mile before that they reached an underground room – a man-made cave with corners and angles that could not have been the work of natural erosion. Even more remarkable, it wasn’t square or rectangle, but a perfectly symmetrical dodecahedron.

“Alien-made, possibly.” Mike revised his first impression as he looked at the way the rock surface had been fused to produce a hard, glassy shell. “What’s in all these containers, anyway?”

Dozens more of polyhedrons that stacked neatly against the walls, looked like plastic, but when Sarah Jane touched one of them it was cold, more like quartz or some other crystalline form.

“I don’t know. There’s no obvious way of opening them,” she replied. “Wish I had The Doctor’s sonic screwdriver. They look like something nasty. I think I’d like to leave them well alone.”

Mike agreed. He turned off his torch and found that the shiny walls were also very slightly glowing so that extra light was not only unnecessary, but likely to give them away as they drew closer to whatever the aliens were doing down here.

They moved on from the storage room along a glowing passageway with doorways – neatly cut regular polygonal doorways – into even more dodecahedron shaped storage space, some of the rooms jammed full of the polyhedron containers. Other rooms might, possibly, have been sleeping quarters for a group of crystal-based aliens. Long, narrow bunks without mattresses, pillows or blankets were attached to each wall in three tiers. In the middle of the rooms were low tables – dodecahedron shaped. Personal possessions didn’t seem to be important to the crystal people. That was just about all there was in their rest quarters.

Mike counted how many bunks in each room and guessed there were about a hundred aliens in this underground complex.

“Less the one I killed,” Sarah Jane said mournfully.

“Still leaves the odds rather in their favour,” Mike noted. “Stealth is the order of the day.”

After a few more minutes of careful progress the tunnel widened out into an even bigger alien-made room. This one might even qualify as a ‘cavern’.

And it was not empty. Most of the estimated number of aliens were at work at a long conveyor belt where those polyhedron containers were rolling out of a large machine, itself of an organic, crystal appearance. Along one long wall was what could only be described as an organic computer. There were no metal parts, only crystal and the sort of limestone that the bedrock around the cavern was composed of. The dozens of screens with data scrolling over them were made of the same shiny surface as the walls, created by extreme heat applied to a rock surface.

There was a Human being standing at the computer, feeding information into it through a crystal keyboard. He was intent on his work and didn’t speak to any of the aliens except to give them instructions.

Which, to say the least, was an odd way for a prisoner to behave.

“Ransome?” Sarah Jane asked as she and Mike hunkered behind a stack of canisters and watched what was going on.

“He looks more like he’s in charge – at least of the computer,” she continued. That he wasn’t in charge of the whole operation became apparent as an alien even taller than his comrades, with a head-glow a deeper green than the others demanded to see the prisoners. Sarah Jane suppressed a gasp as The Doctor and The Brigadier were brought through an entrance on the opposite side of the cavernous production room.

“THIS is what you spies were looking for,” said the alien leader with the same hissing, sibilant tone as the others but a better grasp of vernacular English. “Take a good look before you are destroyed. It will do you no good, after all. Our plans are already too far advanced.”

“Now look here,” The Brigadier began, but seemed unable to express what he wanted the alien to look at.

“‘Spies’ is a case of the pot calling the kettle,” The Doctor protested. “You ARE the invaders here on Earth, after all.”

“Quite so,” The Brigadier managed. “Invaders, spies, traitors… definitely a threat to the British nation.”

“To the PLANET,” The Doctor reminded him.

“You are spies, and ineffectual spies at that,” the alien leader responded. “You were taken easily.”

The word ‘ineffectual’ sounded odd in the sibilant alien voice. It almost echoed off the walls.

“We are not spies,” The Brigadier insisted. “We came looking for my friend, Professor Ransome… your hostage.”

“Ransome is not our hostage, he is our ALLY,” the leader replied.

“What?” The Brigadier was appalled. “Preposterous. James Ransome would never betray Queen and Country by throwing in his lot with aliens.”

“My dear Alistair….” Ransome himself turned from his work and approached the pair of prisoners. “You have it all wrong. I’m not betraying anything. The Archans are friends to the British Commonwealth – indeed, to western society as a whole. That is why I am working with them.”

“Working….” The Brigadier was appalled. “Working with aliens… are you mad?

“That IS a case of the pot calling the kettle,” The Doctor remarked to The Brigadier, waggling his eyebrows in a manner that seemed curiously alien in itself.

“Enough,” the Archan leader said as The Brigadier turned to reply to The Doctor’s comment. “These two ARE known to you, Ransome?”

“Not this chap,” Ransome answered, nodding towards The Doctor. “Though I believe he DOES work for U.N.I.T. But Alistair is an old friend and colleague. You may be sure of his co-operation.”

“You can be sure of nothing of the sort,” The Brigadier remonstrated. “James, what on Earth are you talking about?”

“The Archans are on our side. They contacted me two months ago, and asked for my assistance in their project. They needed a safe place to work and some help with the computer programming. I know my absence must have caused a bit of concern, but the secrecy was necessary. All will become clear once the project is finished. The benefit to western society will be immense. You just don’t understand all the facts, yet.”

“I understand that you have lost your mind,” The Brigadier insisted. “James… this is treason.”

In his hiding place Mike bit his lip. He had heard those same bitter words from The Brigadier’s lips himself. He knew how they stung. James Ransome looked hurt beyond belief by his friend’s refusal to see his point of view.

The Archan leader was just angry.

“Take these two spies and lock them up,” he ordered. “I will deal with them later. Put a guard on the upper entrance. Make sure no other earthlings come down here before we are ready to begin the test.”

The Doctor and The Brigadier were both ushered away into the corridor Mike and Sarah Jane had entered through. Behind them two guards set off the same way. The two hidden ‘earthlings’ knew it was only a matter of time before the body in the chapel was found and a hue and cry raised. They had to rescue The Doctor and The Brigadier quickly and somehow get Ransome out of the clutches of the Archan – whether he wanted to be rescued or not.

The two Archans escorting The Doctor and The Brigadier came back quickly. They had obviously been locked up somewhere close by – probably in one of the rooms off the main tunnel. Mike and Sarah Jane exchanged glances and then quietly crept back that way.

They found the locked room easily and were relieved to see that it was merely bolted from the outside. It was easy to open.

“What are you two doing here?” The Doctor demanded as they stepped into a storeroom containing yet more of the polyhedron containers as well as the two captives.

“More to the point, what are YOU doing here?” Sarah Jane demanded.

“I picked up a signal with the sonic screwdriver,” The Doctor replied, holding up the infinitely resourceful tool proudly. “I woke Alistair and suggested that we check things out quietly. We found an Archan guard down on the beach just below the coastguard lookout. There used to be open cast mineral mining there years ago. At some point exploratory tunnels were excavated. Perhaps they intended to do some deeper mineral extraction. The Archans have extended them considerably.”

“You two went off without us?” Sarah Jane said accusingly as if that was the only point that mattered.

“We didn’t think it needed a crowd,” The Brigadier explained.

“Just as well we were alerted by the radio transmissions,” Mike said. “Otherwise who would rescue you?”

That question was suddenly a moot one. The door was slammed shut and they heard the sound of the bolts being drawn.

“Oh no!” Sarah Jane groaned. “Why did we stand around chatting when we could have been getting away?”

The Doctor sat down on a stack of polyhedrons and sighed deeply.

“Do you know what the Archans are?” Mike asked. “Have you seen them before?”

“Never heard of them,” The Doctor admitted. “But I am quite sure what they’re up to is NOT for the benefit of mankind. They wouldn’t need all this secrecy if that was the case. I can’t imagine what they told Ransome to make him betray his own kind, but they have mischief in mind, that’s for sure.”

“These containers….” Sarah Jane said. “They have something to do with it.”

“Yes,” The Doctor continued. “It seems to be the reason they’re here.” He looked at one of the containers carefully, then took out his sonic screwdriver and scanned it. “This seems to be just ordinary local limestone ground down very finely. It has no radioactive qualities or anything that makes it valuable.”

“So basically, they’re stockpiling cement?” Mike surmised. “It doesn’t make any sense at all.”

Nothing made sense except the knowledge that they were all prisoners.

“Perhaps I could get the door open using the sonic,” The Doctor suggested after a short but uncomfortable silence when they had all run out of questions without answers. “If the bolts are crystal, I ought to be able to resonate them in such a way that they will break apart.”

“Go for it,” Sarah Jane told him. Mike and The Brigadier watched without comment as the small room filled with the static whine of the sonic at work. They were fighting men. Resonating crystal wasn’t something they were trained to deal with. When the door was open, it would be their moment.

The door opened long before The Doctor had resonated the crystal. Mike Yates got ready to attack whatever came into their cell but was distracted to see that it was Ransome.

He didn’t come voluntarily. An Archan guard pushed him into the room and locked it again. The Doctor continued his resonating while The Brigadier questioned his friend.

“I have been a fool,” Ransome said as he sank down onto one of the containers. “A complete and utter fool… and I HAVE betrayed everyone on this planet… west and east….”

Mike turned his gaze away from everyone. He knew how Ransome was feeling all too well.

“Go on,” The Brigadier prompted his friend.

“The Archan leader… I tried to persuade him to let you all go. I assured him that you would be allies to the Archan cause… and he laughed… a cold hard laugh. He said that they needed no Earth allies. He said that they had worked in secrecy until now, allowing the Human population its ignorance of what was to come. But… but he said that Earthmen will breathe their last in a few more days. The planet will be made into a new Archan homeworld.”

“So it is all about invasion,” The Doctor commented. “But then what is all this about… the mining operation, boxes full of crushed limestone…”

“To commit genocide,” Ransome answered. “Genocide on the Human race. They intend to seed the atmosphere of Earth with these containers.”

“What would that achieve?” The Brigadier asked. “Dust in the air… surely….”

“It would be Armageddon,” The Doctor replied. “The amount of containers they are producing here… It would form thick, impenetrable clouds over all the Earth’s landmasses… it would mix with the water in the atmosphere and rain down choking, acidic liquid, killing the people, animals, all plantlife. It would pollute the air and turn the rivers acid, make the planet uninhabitable for centuries.”

“Monstrous,” The Brigadier commented.

“But possible?” Sarah Jane asked. “It sounds a little far-fetched.”

“Very possible,” The Doctor replied.

“And you leant yourself to this insanity?” The Brigadier demanded of Ransome.

“They told me it was a weapon to be used against the Communists… against enemies of our way of life. I thought they were going to give control of it to the NATO alliance.”

The Doctor made a distasteful sound in his throat. His opinion of Human factionalism was well known.

“You are a blithering idiot,” The Brigadier told Ransome. “Even if that was the truth, do you really think we would use such a weapon? I have been to countless international conferences trying to put an end to the use of chemical and biological weapons. The West would NEVER countenance such a thing.”

“Are you sure about that, Brigadier?” The Doctor asked. “From everything I’ve seen of this planet, not everyone is as honest as you, and the possibility of ending the Cold War with the ultimate doomsday weapon might appeal to some of your world leaders – even the western ones.”

“He’s right, you know,” Sarah Jane remarked. “They would.”

“Well, seeing as they lied, anyway, there is no point in arguing about it,” The Brigadier conceded. “The WHOLE world is under threat and they have to be stopped.”

“It must be done now,” Ransome said. “Before they complete the rocket that will deliver the payload into the atmosphere.”

“What’s with all the containers piled up in the chapel?” Mike asked. “Why are they doing that?”

“They’ve taken some of the pods up there?” Ransome was shocked. “Oh… no.”

“What?”

“I think they’re going to do a localised test. They must be going to seed the local area.”

“It will kill everyone….” Sarah Jane was appalled. “Mr and Mrs Freer and their children, dippy Mrs Atkinson, the Colonel… the coastguards and their family.”

Somehow, when she thought of the whole planet being obliterated by choking dust it didn’t have as much impact emotionally as thinking of those few people she could name who lived in this remote corner of a Dorset peninsula directly above the alien threat.

“They have to be stopped NOW,” The Doctor said. He resumed his effort at resonating the crystal. Just as the noise was starting to loosen Sarah Jane’s fillings and Ransome was complaining of a headache, he stood back in triumph. Not just the bolts, but the whole door suddenly crazed and shattered, falling away with a noise that echoed down the corridor.

“They’ll have heard that,” Sarah Jane pointed out.

“Then we have to be ready for them,” Mike replied. “We KNOW their weakness. A blow to the head has the same effect as resonating crystal. We must have no compunction about it, this time.”

To that end, The Brigadier placed himself at the shattered door. When the first Archan came running to find out what had happened he smashed the business end of his swagger stick between its eyes. The skull crazed and shattered. Mike took out the next one with the heel of his shoe.

“Full retreat, out of here,” The Brigadier ordered. “We can’t fight them all on our own. We get back to the hotel and I’ll call in the troops.”

Mike led the way along the passage that would bring them to the chapel. The Brigadier brought up the rear with Sarah Jane and The Doctor between them. They fought six of the Archans in all, leaving them with shattered heads, before they finally reached the surface. Mike dispatched one more of them in the chapel, the last guard left there to protect the pods that had been piled into the ancient building.

“Wait a minute,” The Doctor said. He scanned the room with the sonic screwdriver and then moved aside some of the pods. “Great Heavens!” he exclaimed. “Look at THIS!” He carefully detached a heavy crystal-formed box that was wired up to one of the pods. “This is how they meant to ‘test’ detonate this little lot. There’s enough explosive in here to turn this chapel to so much gravel on the way to devastating the neighbourhood.”

“Give me that,” Ransome said, snatching the detonation pack from The Doctor before he had chance to object. “I’m going back down. I might be able to do something to delay them….”

“I can’t let you do that,” The Brigadier argued. “I came here to FIND you, for heaven sake.”

“You found me, and I was found wanting,” Ransome reminded him. “Now I have a chance to redeem myself. Go on. I’ll follow when I can.”

With that he turned and hurried back down the steps to the tunnel. The Brigadier was distraught, but his first plan, to raise the U.N.I.T. troops, was the only thing to do. He reluctantly abandoned his friend and set off with the others back towards the hotel.

They had got as far as the coastguard cottages when they all heard the muffled crump of an underground explosion followed by a ground tremor that almost swept them off their feet. The Brigadier turned quick enough to see a brief flare of light along the part of the headland where the open cast mining had once taken place and the Archans had found an easy way to make their underground lair.

“Ransome?” The Doctor queried.

“Yes,” The Brigadier replied.

“He could have escaped,” Sarah Jane suggested, but she was the only one who thought that possible. The Brigadier and Mike took the death of their U.N.I.T. colleague with the sort of stiff upper lip stoicism the old Colonel would have expected of them. The Doctor shook his head and bemoaned the loss of life – Human and Archan.

She burst into tears. She didn’t know Ransome. She agreed with The Brigadier that Ransome had been a fool. But she felt sorry for his death. Mike Yates put his arm around her shoulders and comforted her as they continued on their way.

U.N.I.T. arrived with the dawn at The Brigadier’s command. Even though it was likely none of the Archans had survived, there was still a clean up operation to be done. The story put out to the local people was that an old World War Two arms dump had detonated, causing part of the cliff to collapse into the sea and creating a huge depression in the ground above. Since chunks of cliff fell almost every winter nobody was particularly concerned except possibly the Ramblers Association who would have to accept a slight re-routing of their coastal path.

Mike Yates was the one who was most affected by it all. He summed it up to Sarah Jane as the two of them sat in the hotel conservatory watching the Freer boys playing secret agents again and the Colonel taking his ‘constitutional’ around the garden.

“I admire Ransome for what he did,” he said. “I sometimes think I ought to have done something like that, myself.”

“You mean… got yourself killed?”

“Nobody will ever know how he nearly betrayed his country and he died a hero.”

“But he died. Being alive… has to be better than being dead.”

“Not without honour,” Mike answered. “That’s what I lost when I did exactly the same as he did – let myself be taken in by clever sounding lies.”

“You have never lost your honour, Mike,” Sarah Jane told him. “The fact that it matters to you so very much proves that. Besides, The Brigadier is pleased with you. He’s going to reverse the dishonourable discharge.”

“I’m grateful to him for that.”

“So if he’s forgiven you, time you forgave yourself,” Sarah Jane told him.

“That might take a little longer,” Mike admitted. “But I think I might be on the way.”