I looked at Rogers in disbelief.
Was it possible that there was a traitor amongst us?
Joe jumped down from the cargo hold onto the tarmac, still holding the rucksack.
"You have to believe me, Joe," Rogers said. "I had nothing to do with that tracker being in my bag."
"Someone put it there," said Joe. "We all stowed our own rucksacks in the Cage, and nobody has been near there since."
"Now is not the time for an inquest," I said.
"In case you have all forgotten, there are a group of people running this airfield that we have never met, and there are two of them walking over here at this very moment to meet us. Say nothing about the tracker until we have sorted this out between ourselves."
Two men dressed in ancient RAF officer jackets over collarless shirts, heavy-duty denim trousers, and high boots, joined us. The older of the two wore four narrow light blue bands over slightly wider black bands on his shoulder tabs, indicating his rank of Group Captain. The second officer, presumably his deputy, wore the shoulder tabs of a Wing Commander, one rank junior to a Group Captain.
Unlike my friend, Flt. Lt. Hector Lamb and both men had the skin colour and features of native Argentinians. Unusually, it was junior officer who spoke first, and we recognised the slightly accented British voice of the radio controller.
"Good afternoon, gentlemen. My name is Wing Commander Diaz. May I present Group Captain Godoy, the Commanding Officer of this base?"
The older man bowed and smiled.
"Damos La Bienvenida. I speak a little English, but mi deputado is better. El traducirá. You understand?"
I replied that I did and introduced the members of our party. They were ill at ease with the presence of Sol but accepted our assurances that he was a robot with a human mind and entirely loyal. I noticed that Rogers was pale-looking and ill at ease, as well he might be, but that was for later. ….
The deputy asked us to call him Roberto, and I extended the invitation for him to use our first names. We were to call the Group Captain, 'el jefe,' the chief.
Roberto asked us to accompany them to the Mess for refreshments and discussion. When we arrived there, it was empty except for the serving staff. Sol was to tell me later that it was identical to the officers' mess in the other world.
It was no surprise for us to hear that the airfield was run by the resistance. They called it 'el antiquo aerodromo de Nuestros antepasados', the ancient airfield of our ancestors, or most commonly, the shortened version. 'Los antiquos.'
They could not say how old it was, but the Group Captain or 'el Jeffe' had been born here. The son of the previous commanding officer in a hereditary system where power was passed from father to son. There were about fifty other men here on one-year unaccompanied tours of duty. After completion of their tour, they returned to their homes in the subterranean world and were replaced by another fifty men. There was a permanent core of ten volunteer trainers who lived on the base under the command of the two officers. We never learned if they had wives or ever left the base. They never volunteered the information, and we thought it impolite to ask.
During their one year on the base, ten of the men were trained as pilots (They had six Spitfires in total), the rest trained in various support roles. It all seemed to work very well. The officers knew nothing of the time Joe was here in his original incarnation and tricked the machines into thinking that they would develop true consciousness if they relived the emotional highs and lows of WW2 fighter pilots in simulated battle conditions, which was, in fact, actual air combat with the enemy, where pilots lived and died.
Did they ever go out on live sorties against the machines?
Roberto said they didn't. So, what do they do?
"Train our men and wait," said Roberto.
"What are you waiting for?" I asked, "Until you have sufficient trained men to launch a full-scale attack?"
Roberto looked evasive.
"It is difficult to explain," he said, " and I can't say anything until El Jeffe gives me permission."
"Do you ever come under attack yourselves?"
"No," Roberto replied. "This is a barren part of the world. There is nothing to interest the machines, and we are not on the drones' surveillance grid. That is why we knew that the drone that followed you was guided in by a device on the Skytrain. We thought you were in collusion with the drone and the allies of the enemy. In the rare case of unidentified aircraft coming our way, we can usually put up a shielding electronic barrier, a sort of invisibility shield, but it drains our power supplies, and it is never up for long."
"Why did you not activate the shield when you saw us approaching?" I asked"
" We did, "Roberto replied, "but the pilot of the Hurricane bypassed it and let you in. That is why we gave him such scrutiny. This could be of great importance to us, and the pilot has been invited to speak to El Jeffe in private this evening, with only me as interpreter, present."
Roberto refused to be drawn into answering other questions and invited us to inspect our quarters. We went along willingly. We were tired and wanted to clean up and then sleep. But first, we needed to speak to Rogers. …
Our quarters were well-equipped and comfortable. We assembled in a central communal area, and as soon as Roberto had left, the questioning of Rogers began. He was adamant that he knew nothing about the tracker and had no idea how it had got into his rucksack. We were getting nowhere, and then, quite unexpectedly, Jarvis asked him.
"How have you been feeling lately, Rogers? Any different from normal? Are you sleeping well – no nightmares, headaches?"
"I am OK, I guess," said Rogers, "considering what we have been through recently."
"How's your memory?" Jarvis continued. " Do you still remember the basics of your research work at the university?"
"Pretty much, "Rogers answered. "I worked on that project for a long time."
"Care to prove it? Walk me through why the CNO cycle becomes dominant over the proton-proton chain in stars above 1.3 solar masses, and what observational signature this creates in the surface abundances of carbon-12 versus carbon-13 isotopes after the first dredge-up episode?"
Rogers was taken aback but attempted to answer.
" Ah, yes, well... the CNO cycle, right. That's... that's the carbon-nitrogen-oxygen fusion process. So, in larger stars - you said 1.3 solar masses? - the higher core temperatures mean that... um... the CNO becomes more efficient than the regular proton-proton chain because... well, because of the temperature dependence."
He paused, looking confused.
"As for the carbon isotopes, that's... that's related to the convective processes, isn't it? The first dredge-up brings material from the interior to the surface, so you'd expect to see... different ratios. Carbon-12 versus carbon-13... yes, the spectral lines would show this in the star's atmosphere. The heavier isotope would be... more abundant? Or less abundant... depending on the specific nuclear reactions involved."
He trailed off, then attempted to recover.
"Of course, the observational signatures depend heavily on the stellar metallicity and age, so you'd need to factor in the initial composition of the stellar nursery where the star formed..."
"You can stop there, Rogers," Jarvis said. "It was a difficult question to answer off the top of your head. Get yourself a glass of water from the sink, and get one for me, would you?"
Rogers walked over to the other side of the room to get the drinks. When he was halfway there, Jarvis, speaking in the same relaxed tone as before, said,
"Make that two glasses, would you, Komarov?"
"Rogers turned in surprise, "Sorry, professor. I didn't quite understand. Are you talking to me?"
"It's OK, Rogers, just the one glass will do," Jarvis answered.
"What was that all about?" I asked Jarvis.
"I was testing Rogers to see if the agent Komarov had returned and taken over his mind. Do you remember me telling you how, at the beginning, the machines used Komarov as a spy?
He admitted it:
"My name will mean nothing to you, but it is Komarov."
"When did you take over the identity of Rogers?"
"We had been monitoring events at the university after your mysterious disappearance in case you secretly returned. We needed to keep somebody on the ground, and I was the chosen agent. My superiors uploaded my mind to control Roger's brain, and I fully immersed myself in his character. I was Rogers, in public and in private. Well, at first, but he was such an uninteresting character that I often stood back and let him get on with his trivial life."
"Komarov was a far superior scientist to Rogers, and he could not resist the temptation to correct the mistakes in Rogers' work. That is how we got onto him, at the time. The question I just asked Rogers would have been easily answered by Komarov, had he been present in Roger's mind. You saw that Rogers did not have a clue what I was talking about, and that puts him in the clear. I know Rogers, and there is no way he could have planted the tracker on his own."
"But somebody planted it, " I said, and if it was not Rogers, then who was it?