Riley Davenport looked up at the great dome of night sky. Even in the nineteen twenties his London home was already suffering from light pollution and he had learned to value the opportunities his new time travelling life afforded him to look at undimmed stars.

"Orion," he said picking out the most distinct constellation in the north-eastern quarter of the sky.

"Yes," Chrístõ acknowledged. "Beta Delta is in the Orion quadrant - where my fiancée lives. More importantly to us now, it was a constellation that particularly interested the builders of our second wonder. Scholars have written some interesting papers on the positioning of the structure in relation to the position of those stars.”

The stars of the Orion constellation shone down on the Giza plateau in the year 2555 BC, fifteen years after the Great Pyramid of Khufu was begun, and some five years before it would be declared finished. The limestone casing stones that would give it a smooth surface was only just begun and the great capstone had yet to be placed on the top, but it was every bit as magnificent as Riley had been led to believe.

And the entrance to the pyramid was still open. There was a guard, of course, but the two visitors were using perception filters to move through the quiet worker’s quarters in the semi-permanent settlement beside the pyramid. They walked past the guards who did not expect anyone to come along so brazenly.

There were rushlights in the upper passageways, but as Chrístõ and Riley took the descending route, they were soon in total darkness. They moved slowly, feeling their way carefully until Chrístõ judged that they could risk the penlight mode of his sonic screwdriver.

"We're far enough down, now," he whispered. "Our light won’t be seen nor our voices carry - as long as we don’t do anything silly like singing or shouting.”

"I’m tempted to sing," Riley confessed. "I’m in the Great Pyramid of Khufu. It is amazing. There ought to be a song that expresses how I feel.”

"There really ought to be," Chrístõ agreed. “This is the only one of the Seven Wonders to survive to the twentieth century and beyond more or less intact. You will note that we are descending to the lowest chamber, the one dug out of the bedrock beneath the Pyramid.”

“I noticed that," Riley answered. "The thinkers of my time are uncertain of its purpose - the King’s chamber and the smaller but no less ornate Queen's chamber being above and this remaining empty.”

"That’s that easy enough. I’ve been here before,” Chrístõ told him. “I had some friends who wanted to witness the first stones being laid. I had the opportunity of seeing the papyrus scrolls with the plans drawn up on them. The lower chamber is a false one to fool any potential grave robbers. The passage we are following is, as you will have noticed, direct. The true chambers are at the end of well-concealed side passages from this one. There were also a couple of ideas for traps that could be sprung by intruders, but I’m not sure if they were ever implemented. I think the idea is to keep it simple. Anyone stupid enough to risk breaking in will find nothing and go away empty handed.”

"It worked," Riley said. “The Chambers were safe.”

"Until the archaeologists of Europe descended on Egypt in the Nineteenth century," Chrístõ noted.

"But that was archaeology, not theft," Riley insisted.

"It’s not always easy to tell the difference," Chrístõ answered him coolly. "The British Museum has a lot of artefacts that rightly belong here in Egypt or other places where the Empire has plundered. The Elgin Marbles….”

"In the name of history," Riley defended his chosen profession against the criticism veiled in Chrístõ's remarks.

"Relax," he said to him. "I appreciate history, too. But it is probably a good thing that my people have strict rules about souvenirs of time travel. The pyramids would have been moved to the Gallifreyan plains by now, otherwise."

Riley wasn’t wholly amused by that idea. Chrístõ assured him it was not at all likely that anyone from his planet would commit such an act of vandalism.

They reached the lower chamber at last. It was a strange sensation standing there in a space hewn directly from the bedrock of the Giza plateau. They were acutely aware of the great weight of man-made work above them and of the natural formation of solid limestone around and below.

“The node will be safe here,” Chrístõ said, reaching into his pocket for the golden ball with so much unseen and unsensed power within it that it would influence the Human race for a millennium. He placed it on the ground and watched as it buried itself in the bedrock beneath the pyramid where it would never be found even by the most ardent archaeologist or grave robber.

"Job done, let's get out of here now, before they want to bury us in here."

It was a joke, but the idea of being entombed in the pyramid disturbed Riley. The great mass above him troubled him far more as they set off back up the passageway that led in a northeasterly direction out towards the night sky dominated by Orion the Hunter.

They were still only partway up the steeply angled slope when the vibrations began. Almost unnoticeable at first, they rapidly became a violent shaking that made them grasp the few handholds to be found in the good mortar that held the strong stones of the walls together.

"It’s an earthquake!" Riley exclaimed. "We'll be buried alive. No... we couldn’t be. The Pyramid still stands in my day. Nothing happened to it."

"It's not an earthquake," Chrístõ told him. "The vibrations are coming from above, not below, and they're too regular for any kind of natural force. It feels more like... like...."

His theory was cut off by the sounds of fear and running feet. Two of the guards from the entrance to the pyramid ran straight into them. They were followed by a young woman bearing a basket of bread and a flagon of water who had obviously been bringing refreshments to the men. She blundered straight into Riley’s arms. It occurred to him that people in crisis like this were impervious to the perception filter. They saw them clearly.

“Who are you?” she asked fearfully. “Why are you in the Pyramid?”

“It doesn’t matter,” Chrístõ answered, with a strong measure of Power of Suggestion that made the question vanish from everyone’s thoughts. “The real question is what you three are doing in here.”

One of the men was bleeding from the mouth. He had been so scared he had bitten through the tip of his tongue. Chrístõ gave him a clean linen handkerchief to staunch the flow and turned to the older, more experienced, but still terrified man.

"What's happening?" he repeated. "What have you seen?"

"The stars put out," the man answered. "The gods have sent a great chariot of iron to punish the unworthy."

"A chariot?" Riley queried.

"From the gods... blotting out the stars. I think he means a space ship. I think Egypt is being invaded by aliens. "

"Is that... it couldn’t be...." Riley protested. "That never happened."

"It didn’t, but it is happening now, so lets not waste time disbelieving."

The one who had bitten his tongue was close to fainting from loss of blood and fear. His comrade and the woman were trying to support him.

"He’s in no fit state to do anything," Chrístõ told them. "Go down to the chamber and rest there. We'll find out what's happening up there. It has nothing to do with your gods. Be sure of that. The gods of Egypt want nothing more than the crops planted and harvested at the proper time and the Nile ebbing and flooding in its own proper course. This is a work of evil beyond their command."

Riley watched Chrístõ speak with a command far beyond his apparent years. The Egyptians with no reason to listen to him – a foreign intruder in their sacred Pyramid - were assured by his words and obeyed his instructions.

"I rather wish I was going down there to hide," Riley admitted as they resumed their climb to the north-east entrance. "This is frightening."

The vibrations had stopped now, but the sounds of people screaming and crying in panic were filtering down towards them.

"Down there is a slow death from hunger and thirst if we don’t put a stop to what's happening," Chrístõ told him. "I think you have the courage to risk a quick death fighting it out. I'll try to find a way to avoid that, if I can. But come on... let's see what we are up against.”

Riley had never seen any of the films from the late twentieth century in which alien ships hovered over earth cities blocking the sunlight and frightening the residents. He had no basis for comparison when he saw the huge, scarab shaped ship hanging over the Great Pyramid of Khufu. It was the first alien ship he had seen at close quarters and it was terrifying even without the sight of the aliens themselves emerging from silvery egg-shaped landing craft and fanning out to surround the workers and their families as they emerged from their homes to witness the chariots of the gods descending.

“What is it with aliens and Egypt?” Chrístõ murmured as he pulled Riley down on the edge if the pyramid entrance, out of sight of the invaders but with an unobstructed view of what they were doing to the people.

There was resistance and protest, of course, but those who tried were met brutally, not by killing the ringleaders, but by random murders, meant as examples to the rest. With the burnt bodies of innocent victims at their feet, the captives were soon quiet and compliant. They allowed the aliens to separate the working men and boys from the women, children and elderly. At first there was a palpable fear that the vulnerable group might be slaughtered, but it seemed that the aliens had learnt the value of hostages. Those deemed as 'unproductive' would be the guarantee of non-resistance by the rest.

“What are they?” Riley asked.

"Sontarans," Chrístõ answered as he listened to the gruff voice of the alien commander telling the captives how they were going to be of use to the 'glorious cause'. "Brutal, cruel, and deaf to any plea for mercy. They are cloned as battle ready soldiers with no interest beyond their war with the Rutan Host. That war has been going on for about a century in this time. When I was born... which is getting on for three thousand years in the future from now... on the day I was born, my father was trying to negotiate a peace treaty. It had been broken before my official naming ceremony and they have carried on fighting ever since. The duration of the war is further complicated by their discovery of time travel and warp shunt technology. Now they can fight before their war even began in linear time and make any planet in the cosmos their battleground."

“And that’s what they’re doing here?”

Riley looked at the short, stocky, helmeted troopers with their deadly weapons and shuddered. He still couldn’t understand how such a thing could be happening in the past history of his world. Chrístõ hadn't even begun to explain about timelines and temporal cause and effect that meant the history he knew could have changed by the time he returned to the future.

Chrístõ had not explained, either, about the more likely ability of humans to forget what didn't fit their comprehension -like alien invasions in societies who thought the stars were lamps held up by the handmaidens of their gods. He didn’t mention that history would forget this anomaly.

Because it was down to the two of them to put a stop to what was happening, and until they achieved that feat, with the odds stacked high against their success, the people of the Giza plateau couldn't begin to forget about it.

"What do they want these people for?"

"Slave labour," Chrístõ answered without hesitation. "That’s why they didn't kill the ones who tried to fight. They chose weaker targets to use as examples. They want strong, capable slave workers for something."

"What are we going to do about it?" Riley asked. "Two of us against that lot with the sort of weapons they have.”

"It’s not just that lot," Chrístõ had counted as many as thirty Sontaran troopers rounding up the workers. But the ship overhead could have hundreds aboard. His plan had to be two-fold, dealing with the mothership and with the troops deployed on the ground.

"Let me help," said the man Chrístõ had sent down into the chamber. He had returned with news that his friend was sleeping now, tended by the woman. He looked angrily at the sight of the Sontarans making slaves out of free men who had built the Great Pyramid from the first foundation stones to its incredible height not as forced labour but as paid, skilled workers who took justifiable pride in their achievement.

"What's your name?" Chrístõ asked. "I'm not sending any man to risk his life without knowing his name."

"Aaro," he replied. "I have a spear and a knife. I can take two of those fiends to meet the gods along with me."

"No valiant but futile sacrifices of that sort," Chrístõ answered him. "Leave your spear. It is too long and inflexible and it marks you out as a soldier. Riley, I want you and Aaro to get down there among the captives. I need you to tell the strongest and the most determined that they CAN fight back. They outnumber the Sontaran guards by twenty to one and all they need to know is the weakness that all of that race have. Once enough of them know... and you see the signal I'm going to give, they can overwhelm them.”

"It’s risky," Riley admitted when Chrístõ explained. "Some of them… some of us… could die.”

"And I don’t know their names... which makes what I said before complete nonsense. But they will be fighting for their own families, their own land. Most men would count that worth the risk of death. I know I did when my planet was invaded. So did many who didn’t make it.”

Riley was uncertain, but Aaro assured them that it was how he felt. Chrístõ watched and judged the moment for them to move from their hidden vantage point. At the same time he moved quickly through the deep shadows of the slowly breaking dawn to the place just outside the work camp where his TARDIS was disguised as a small, nondescript stores building that nobody would ever notice.

With the Sontarans still barking orders and generally terrifying their captives, nobody noticed the TARDIS dematerialising, even though it made the usual animal-mechanical noise and caused the usual displacement of air.

That was the easy part of his plan. The next part was a little harder. He had to re-materialise aboard the mothership, preferably close to either the bridge or the engine room.

“Sontarans think their technology is superior,” he said aloud, though the only listener was Humphrey, under the console as usual, who trilled in a way that sounded as if he was listening and understanding, even though he was doing neither. He was a very good companion in that way. “But really it is only because they have a habit of displaying themselves to cultures with no technology at all who are awed by them. next to Time Lord engineering they are the primitive ones. This ship of theirs has no anti-scanning shield, so I have been able to display a full deck by deck schematic. Nor do they have any kind of anti-transmat field in place. There is nothing to stop me materialising aboard. But first I want to boost this perception filter.”

He took the medallion from around his neck. It had hardly been working at all for the past hour. The Sontaran troops on the ground were too alert for trouble. Even their jar-headed brains could see through something that simple. Their comrades left on the mothership were not expecting anyone in this primitive era to be able to get aboard, but even so they were on high alert and that might just nullify the basic perception field.

“I’ve given it a triple-enfolded upgrade,” he told Humphrey as he put the medallion back around his neck. “Can you still see me?”

Humphrey trilled a reply. Chrístõ laughed.

“Of course, you can. You know I’m here.” He set the co-ordinates for a storage area near the engine room and got ready for the dangerous part of his plan.

The sun was coming up on the Giza plaza and the Sontarans were putting their new slave workers to the task they wanted them to perform. Riley, working on the task Chrístõ had set him, was in the midst of a group who were ordered to carry boxes of equipment from one of the silver egg-shaped craft and take it to the Great Pyramid. Others were set to work digging a moat around the edge of the structure. They were guarded at all times and they were ordered to keep quiet as they worked, but even so, Riley and Aaro between them had started a chain of information that was being passed along from man to man along with the instruction to wait for ‘the sign’.

The sign wasn’t quite ready, yet. Chrístõ was working on it in the engine room. He had walked unnoticed past the guards in the corridor and disabled the technicians inside by the simple if slightly perverse method of inserting his sonic screwdriver into the probic vent at the back of the neck and emitting an electronic pulse for good measure. That was the Sontaran weakness he had passed on through Riley and Aaro to the Egyptians. Curiously, it was regarded as a strength by the Sontarans themselves. They proudly told each other that they always faced their enemies because of it. There was no such thing as a fleeing Sontaran.

But there was such a thing as a busy Sontaran not expecting to be snuck up on from behind. That was Chrístõ's advantage. Now, with the technicians unconscious in a heap on the floor he was able to work quickly reconfiguring the warp shunt engines so that they would start warping without shunting until the ship imploded.

This was where his claim to be a pacifist was seriously tested. He knew that he was setting up the deaths of hundreds of Sontarans aboard the ship. It was something he had to justify to himself. Of course, the Sontarans were the aggressors here. He was simply fighting back in the only way he could. The Sontarans had already drawn blood when they killed innocent and unarmed victims.

Besides, the Sontarans were not even natural lifeforms. Cloned soldiers with no culture but war, war at all costs to other races, did not merit the same consideration as their victims.

No. That was a philosophy he would never accept. All life, even wrong-headed clones like the Sontaran was important. Their souls weighed as heavily on his as any other. He prepared to kill them with deep reservations and even deeper regret that there was no other way.

The sabotage would take eight minutes to become critical and irreversible. That was time enough to get back to his TARDIS and get away.

At least it would have been if there weren’t two Sontaran troopers standing near the storeroon where his TARDIS was parked. Had it been discovered? Certainly the perception filter was still working. He got close enough to hear one of them talking on a communicator to the bridge.

"Come," the Sontaran said to his companion. "There is something wrong in the engine room. We must investigate."

Chrístõ murmured a low Gallifreyan swear word. It was too soon for anyone to discover what he had done. It still could be reversed and the plan would be ruined - to say nothing of his hopes of preventing alien intervention in Giza.

"What was that?" asked one Sontaran. His swear word had been heard. The troopers both raised their weapons. The first was zapped by the sonic screwdriver to the probic vent a moment later. The second almost managed to see Chrístõ's arm sweep around to take him down as well. He stepped over the probe figures and dived into the storeroom. He had to hope that there were no more troopers close enough to investigate the engine room before the eight minutes were up.

"Cross your fingers, Humphrey," he said as he closed the door. "Yes, I know. You don’t have fingers. Its just superstition, anyway. I shouldn't need to cross any fingers for luck. Not if I’ve crossed the wires properly. And while I’ve been talking to you, I've been preparing another little shock for the Sontarans - on account of their lack of shielding for their computers and the fact that my TARDIS is a far superior system and I'm a really good computer programmer."

Humphrey trilled encouragingly. Christo smiled briefly at his own cleverness then reminded himself that he was just a few minutes away from committing mass murder.

The TARDIS landed back at the side of the Great Pyramid with half a minute to go. Chrístõ noticed that the Sontarans were sending their slave workers into the pyramid with boxes of electronics. He knew what they were for. He had seen the plan in their unshielded computers. That was something to deal with later. For now he just had to wait for the signal he had promised.

It started with all of the landing craft taking off at once, responding to the recall signal he had looped into the mothership's communications array. The fact that a few Sontarans were aboard the landing craft where they were offloading the mysterious equipment was a bonus on top of the distraction the departure of the ship caused.

The simultaneous removal of the mothership to the outer troposphere and its subsequent implosion thoroughly disorientated the rest of the Sontarans. The Egyptian workers were ready. Knives, broken pieces of spears, anything they had managed to secrete within their clothes was brought out and thrust into probic vents. The Sontaran troopers discovered too late that even a momentary distraction was enough to let an enemy get behind their backs.

The insurgency was swift and deadly. True, there were some casualties, but the Sontarans suffered worse. After being brought down by the assault from behind, they had been set upon by the angry crowds. Christo was startled to realised that he had never seen Sontaran blood before - still less a decapitated one. The body of the commander of the landing party had suffered a very ignominious death.

When the head - still in the helmet - was tossed in the air like a football by the triumphant Egyptians knew it was time to restore a sense of order.

"You've won," he told the crowd once he had achieved that order. The wounded were being attended to, including the man Chrístõ had sent to the lower chamber. He was being given specially tender care by the young woman who had hidden with him until it was safe to emerge.

"You've won,” he repeated. “The ashes of your enemy's sky chariot are falling around you." A fine layer of grey-white with a metallic taint to it was settling over the Giza plateau. It would dissipate in time, along with the memory of the destructive power of warp shunt drive overload. "Now you must do the right thing by your enemies. Their bodies must be burnt. Their ashes must join those who were destroyed already. Their weapons must also be burnt. Your gods would not wish you to have such terrible power in your hands. Destroy the strange tools they brought, too. Leave nothing of them to remind you of their coming. Let no account of this night be written upon papyrus or engraved upon stone, no songs or stories told. Let this be forgotten while your true legacy, this Great Pyramid of Khufu, becomes your monument for eternity."

It was done as he commanded. In the evening of the day on which the pyramid builders of Giza began to forget their brief encounter with warriors from beyond the stars, Chrístõ and Riley slipped away to the TARDIS.

"It took a lot of Power of Suggestion to persuade them to stop using a Sontaran head as a football," Chrístõ said. "I might not be able to keep it up if they start to realise we turned up at about the same time as the aliens. Time we were off."

“We didn’t even find out what it was all about,” Riley said as he watched Chrístõ set their next destination. “Why did the Sontarans come to Giza?”

“I found out,” Chrístõ answered. “It was in their computer. The one my TARDIS was able to read so easily. They wanted to establish a communications array – using the Great Pyramid as a focal point. They were going to send false messages urging the Rutan Host to come here – where they would ambush them, of course. The consequences for the Human population of Giza - for the whole cradle of civilisation as we know it – would be terrible. Even after we defeated them, if I hadn’t made sure all of the weapons were destroyed then the work the Guardians set me to do would have been for nothing. Egyptians fighting their neighbours with Sontaran blast guns would alter the course of history irreparably.”

Riley had been doubtful about the work Chrístõ had been sent to do, but as he contemplated the subjugation of north-Africa, of the Mediterranean, in such a way, he thought he understood why it was needed. He was ready, now, to join in the work wholeheartedly.