‘Take an electron moving forward in time,’ Kenna remembered one of Rhianna Chiang’s childhood teachers saying, ‘and try to distinguish it from the behaviour of a positron moving backwards in time – and you’ll find there is no difference, so how can you decide which it really is? It follows logically – and is actually true – that subatomic reactions are reversible in time.’

The teacher had shown footage of a smashed egg leaping up into someone’s hand and spontaneously reforming.

‘You know I’m showing this in reverse. But only vast collections of particles, like the number of atoms required to make up an egg, show timeflow in their larger structure. At the atomic or subatomic level, footage going forwards or backwards is equally likely.’

At an early age, Pilots were expected to understand time-flow as an emergent property. But there was a twist in the tail regarding realspace, and if an equivalent was unknown in mu-space, that might be only because Labyrinth’s researchers had not found it yet.

Because of the startling exception to the rule: neutral kaons and their opposite-spin antiparticles appear to know the difference between past and future. Seven centuries of data backed up that observation.

Now the present Lord Avernon was looking at readings that appeared to show a K° imbalance in the wrong direction, as though time itself were wobbling, as if the present were threatening to flow from the future into the past.

And if he were the one to monopolise the technology accruing from this phenomenon, not only would Demesne Avernon be a duchy once more, he would become a Lord Primus and probably—

‘Father! My Lord!’

—have better servitors, ones who would know to bar his over energetic son from his private laboratory chambers, even if he had not issued instructions to that effect.

‘What is it?’ He gestured the holos into non-existence, because the boy was bright and you never knew what he might notice. ‘Tell me there’s a good reason for this outburst.’

‘More an inburst, surely,’ said young Alvin. ‘But we’ve a visitor and you’ll never guess what he is.’

‘You’re right, I won’t guess. Just tell me.’

Alvin looked disappointed for a moment; then he gushed: ‘His name is Caleb de Vries and Mother’s talking to him in the Great Hall and he’s a Pilot, Father. A Pilot!’

If people, deep in their underground strata, rarely thought about the planet’s surface, then they had almost forgotten about mu-space and the Pilots who had brought their fore-bears here. Nor was this a culture that had come about by accident; deliberate design ran through customs, politics and language. But of course the Lords and Ladies still, on occasion, dealt with Pilots as required.

So long as the others, the servitors and commonfolk, forgot about the rest of inhabited space, that was good enough. Isolationism was a tool for social engineering, not an end in itself.

Today was nevertheless doubly unusual. Kenna, observing, felt an unexpected excitement.

It had been so very long since she had seen a Pilot.

Pilot deVries stood in formal jumpsuit, black edged with gold, with a knee-length black cape that was more than a simple garment: it could if necessary become shield or weapon. For an offworlder, he made a decent job of the nuances in bowing to the correct angle, with leg turned correctly, as Lord Avernon entered the Great Hall. The Lady, from her ornate chair, smiled approval.

‘My Lord,’ said deVries. ‘Lady Suzanne was just pointing out your grandfather’s work.’ He gestured at the holoscape showing in an alcove. ‘A deliberate unbalancing of the golden ratio to produce a visual momentum, combined with a fractal dimension of 1.66 throughout.’

‘Indeed, sir,’ answered Avernon. ‘My Lady is privy to more than art appreciation.’

It was an indirect way of indicating he could discuss business.

‘Pardon my intrusion,’ said deVries. ‘I gather that you lodged interest in commissioning a voyage, before the Lords Major at the Regional Convocation.’

The high point of that Convocation, some fifty days past, had been the upraise of a servitrix to noble status, by virtue of her enormous self-discipline in using every educational opportunity available, and her superlative work. Now she ruled her own demesne in Penrhyl Provincia: a shining example for every commoner, except that upraise occurred maybe twice a century, no more.

But most of the actual work done during Convocation had been the usual – trade negotiations, strengthening or reshaping political alliances – during which Avernon had indeed lodged a discreet request.

‘Not exactly a mercantile voyage.’ Avernon’s tone lightened. ‘More along the lines of logosophical investigation.’

‘My Lord?’

‘I’m looking for a sequence of short flights in ever-wider orbits of Nulapeiron. Additional data to build on spacedrone investigations we’ve already carried out.’

(In Kenna’s judgement, the we in that sentence was unjustified.)

‘The details are in here,’ added Avernon, holding out an infocrystal. ‘Will you be able to carry out the work?’

Pilot deVries took the crystal and scanned it with his tu-ring. ‘Absolutely, my Lord.’

‘Then we’re done here.’

‘My Lord.’

As deVries bowed out, his obsidian eyes turned to an ordinary looking patch of wall that formed one of Kenna’s thousands of covert optical sensors, and then he winked. Inside herself, Kenna laughed: Pilots were as sharp as ever.

In contrast, Avernon had forgotten or never bothered to realise that Kenna’s distributed presence reached this far.

‘Pilots.’ Lady Suzanne continued to stare at the grand door-way after deVries had exited. ‘Are we still so dependent on them?’

‘Not so much,’ said Avernon. ‘But what would it be like, my Lady, if you could perceive events that were to come? How much power would accrue from such an ability?’

‘None at all, my Lord, if what you saw was your own ruin.’

Avernon blinked several times.

(And again, Kenna was amused.)

‘I’d be interested,’ Lady Suzanne added, ‘in how one might engineer such a thing.’

‘It’s, um, early stages yet.’

‘And when do you foresee those ideas maturing?’ Then she laughed and placed her palm on Avernon’s arm. ‘Forgive me, love. I’m only teasing.’

‘Yes, well. Of course you are.’

Then Lady Suzanne signalled for the palace steward to attend, and summoned up holo lattices of accounting data – Palace Avernon’s upkeep was a complex matter. As her steward stood before her in his white-and-platinum livery, cane of office in hand, he responded to his Lady’s questions and gave occasional recommendations, which she accepted. Lord Avernon gave the occasional nod, his attention elsewhere.

(Kenna followed his example, searching the Palace systems for deVries.)

In realtime she saw this: Pilot deVries stopping in a deserted corridor, kneeling on the floor, and keeping that pose as the quickstone whirled and he sank downwards, and out of sight.

*

The person that deVries met four levels down – still within the Primum Stratum, a lower level of the Palace complex – was a thin, hard-faced woman in the clothing of a drudge: an epsilon-level servitrix at best. Except that to Kenna’s perceptions, the smartlenses were obvious, and so was the conclusion: the woman was a Pilot living in deep cover.

‘I’m Linda Gunnarrson,’ said the servitrix.

‘Caleb deVries.’

‘Let’s get my standard report out of the way.’

There was a flash of light from deVries’s tu-ring.

‘Got that,’ he said. ‘You’re doing a good job, clearly. Any concerns?’

‘I don’t need the case officer pep-talk, deVries. All I want is—’

‘Working off the sins of the father?’

Gunnarsson flinched. ‘So you did your homework. But my father wasn’t— You think I’m after redemption?’

‘I’ve done the time-distorting hellflight bit myself. But look . . . My sister died on Göthewelt. I don’t blame your father for the Zajinet raid, and I sure as hell don’t blame you.’