Then Polly said out loud, ‘So they think I’m some sort of demon now?’

Demon, messenger, oracle… they don’t seem able to make up their minds, the watcher opined, noting the slave standing behind the girl, scribbling down her every utterance on a piece of parchment. Talking out loud to her AI companion, had probably been what had clinched it because it was quite obviously not an act.

Now also sitting on the edge of her couch, the girl listened and responded as best she could when Claudius addressed her. Otherwise, her attention was inevitably focused on the platters of food the slaves kept bringing: fish served in a fragrant sauce, meats with sweet and crunchy coatings, dried figs and fresh apples. She even worked her way through a whole platter of oysters. Noting Claudius eating his way through a large plate of mushrooms, and then checking her database again, the watcher whispered to herself, Now that’s a preference he’ll come to regret.

But there was little enough going on here, and tracking forward the watcher observed that guests not yet departed were falling asleep on their couches. Claudius himself was snoring like a malfunctioning chainsaw and soon four slaves came in to pick up his couch, and carry it out of the tent—the troop of Germanic guards falling in behind. Two female slaves entered silently, but shortly made it understood that Polly should accompany them. She was led off to another tent, lit by an oil lamp, and containing a bed covered with furs and silks. The girl imperiously waved away the slaves when they attempted to undress her and, taking off only her boots, collapsed and was instantly asleep.

Enjoy it while you can.

The watcher skipped over the night into the next day and observed the killing.

‘About two thousand years in your future,’ Saphothere replied to the question Tack would have liked to have asked him long ago. ‘After the Muslim jihad and the ensuing resource wars, after the nuclear winter that resulted from those wars, and after the fall of your whole civilization through your tendency to breed weak humans and strong plagues.’

Tack dared to reach out for the bottle and topped up Saphothere’s then his own glass. ‘Weak humans, strong plagues?’

Saphothere took up his glass and downed half its contents. ‘You were already witnessing it in your age: hospital superbugs, variant pneumonias, air-transmitted HIVs. Ignoring the fundamental facts of evolution, you used antibiotics in excess, by this artificial selection process thus producing bacteria resistant to antibiotics. And that is only one small example.’

Much was already being said to that effect in his own time, Tack remembered, but there had seemed little genuine will to do anything about it. How could doctors refuse a dying man further treatment on the basis that this would eventually lead to the treatment itself becoming ineffective?

‘Weak humans?’ Tack nudged.

Saphothere stared at him, a faint smile twisting his features. ‘Not something entirely applicable to yourself, but you and those of your kind were a persistent exception.’ He did not explain further, but went on, ‘The ordinary people of your time were coddled in the extreme with drugs and medical treatments, and in your soft, malformed societies the weak and the stupid were allowed, even encouraged, to breed indiscriminately. As the centuries passed, the human gene pool became weaker, while plagues became more common. The second Dark Age began with a neurovirus—for most of humanity a plague contracted in the womb. Like syphilis it ate away at the brain and claimed its victims by the time they reached their thirties. That sorry age lasted a thousand years, until the rise of the Umbrathane.’

‘The Umbrathane preceded you then?’

Saphothere was now grinning openly in a way that could only be described as nasty. ‘Oh yes. They arose from a small interbred group who had managed to maintain a cerebral-programming technology that enabled them to live, individually, decades longer than anyone else on the planet. They spread out from their enclave and took control. Umbrathane: meaning those bringing the land out of shadow. But does any of this sound familiar to you?’

Tack was at a loss to know why it should. This all occurred in a future he would never have reached in his natural lifespan.

‘They came before you?’ Tack repeated, hiding his mounting irritation.

‘Before us, yet with us always. They bred the weakness out of the human race. The Nazis and the Stalinists of your own recent past were nothing in comparison to them: hundreds of millions of weaker beings were exterminated in their camps, and their own breeding programs lasted for centuries. They made the human race strong and succeeded in taking it out into the solar system — before fracturing into various sub-sects perpetually at each others’ throats.’

‘So when did the Heliothane come into being?’

‘There was a catastrophic war… millions killed on the surface of Mars, incinerated by sun mirrors originally used to heat the surface of that planet, but then turned into weapons by a sect which decided that the adaption of the human form to exist in those airless wilds was sacrilegious. Before we named ourselves Heliothane we controlled those mirrors, the giant energy dam in orbit between Io and Jupiter, and other energy resources in the solar system. We were engineers, on the whole, and finally became unable to countenance the destruction of our projects in these petty wars. Finally deciding to act, and with so many power sources at our disposal, we had outreached the Umbrathane technologically and industrially within a decade.’

‘And then?’

Saphothere drained his glass, then refilled it. Tack’s glass was still full, for though he was enjoying the buzz from the alcohol, he had forgotten to drink while this story unfolded.

‘Those who did not escape, and did not accede to our solar empire, we exterminated,’ Saphothere explained.

‘And when did time travel come into this equation?’

‘During that war. For centuries it was known to be a possibility, but that huge energies would be required. One of our own people finally worked out how it could be done, so it was used by us in a limited fashion as a weapon—shifts of a few hours or days only, for we understood how huge a threat this technology could pose to our very existence. Had we gone back to attack the Umbrathane at the period they destroyed the Mars mirrors, we would also have shoved ourselves far down the probability slope. Near the end the one who had first worked out how to use the tech gave it to the Umbrathane and they and he fled into the past. To pursue them, we needed larger energy resources and so laboured on the great project. Two centuries from the destruction of the Mars mirrors, we completed the sun tap.’

‘Cowl, you’re talking about Cowl? This is why you could not kill him in his own past because to do that you would lose the whole technology he was responsible for.’

Saphothere eyed him. ‘You’re not so stupid after all. Perhaps this whisky is loosening some of the knots in your brain. Now, have you worked out the origins of both the Umbrathane and the Heliothane?’

Tack said, ‘The Heliothane are direct descendants of the Umbrathane—if not Umbrathane themselves with a slightly different name and a different agenda.’

‘That is correct. Now consider the original Umbrathane maintaining a cerebral-programming technology for a thousand years. Tell me, how many of your genetically engineered and programmable kind exist in your own time?’

‘Hundreds… but not thousands,’ Tack replied, getting an intimation of what Saphothere was telling him.

‘Perhaps only ten or so years on from when you were pursuing that girl, your own kind break their thraldom to U-gov and become able to choose their own programming. They then become an independent organization, selling their skills to the highest bidders in the wars that follow—as mercenaries. The Umbrathane are the descendants of your own kind, Tack. I am, too. Which is why, for so long in our own period, even though we knew about you being dragged along in the wake of that torbearer, we dared not touch you. But now we are more frightened of what Cowl is doing.’ Saphothere abruptly stood up, drained his glass, and slammed it upside down on the table. ‘Now I must sleep, and build up my own resources for what is to come. One long leap will bring us to Sauros. Then will come the easy journey through the tunnel, back along and beyond all this way we have recently come, to New London.’