The proper subject for contemplation was Javeed, the proper mood a celebration of the fact that they could still spend time together. But in the life Martin had once imagined for them this journey would have been a mere rehearsal, whetting their appetite for the real thing. It was hard to swallow the claustrophobic vision of his health declining to the point where they could rule out actually travelling anywhere: not Afghanistan, not Australia, not even the ruins of Persepolis with the other tourists. Just Zendegi, over and over again – with his body laid out flat, as if he were already in the morgue.

He cut off that line of thought and tried to focus on his memories of the real Kabul. He pictured the crowded city of twenty years before; thousands of refugees expelled from Pakistan and Iran had found their villages too dangerous to return to, and had ended up living in bombed-out buildings in the capital, trying to survive the winters with broken roofs and the only fuel whatever dead trees could be found in the city’s parks. He’d met one family – Ali and Zahra and their four young children – not too far from the bend in the river where Zal’s imaginary party was camped. When Javeed was a little older he would need to hear their story, to hear who’d survived that winter and who hadn’t.

Insects hovered over the mud. The sun was almost directly above now; Javeed was taking too long to return. Martin’s thoughts snagged on a complication: the Proxy needed to be ready to make the right judgement, not only for the six-year-old Javeed, but also for the ten-, the twelve-, the fifteen-year-old – for however long it continued to be invoked. It would have no power to form long-term memories, or be shaped by its experience of watching him grow up; it had to work out-of-the-box with Javeed at any age. The last thing Martin wanted it to do was to treat his teenage son like an infant.

And he was supposed to prepare for that… how? By mentally prefacing every action with a conscious acknowledgement that it might not be appropriate at some time in the future? Well, he’d just done that. Back in the here and now, Javeed was a small child, and he’d either got lost or been caught. That he hadn’t pulled the plug on the whole simulation meant almost nothing – least of all that he didn’t need help.

Martin pushed through the rushes as fast as he could. It was only when he drew close to the camp that he attempted a degree of stealth; he was prepared to risk detection, but so long as they remained in Zendegi he wouldn’t lightly throw away any chance they still had to succeed.

He crawled the last few metres on his knees and elbows; easier than in real life, maybe, but the concentration it took to manipulate his icon through the reeds felt almost as draining as any physical task. Charmingly, the game’s designers hadn’t failed to allow Zal’s party a place where they could feed fertiliser to the river’s algae: a tent had been set up backing onto the reeds, and it was sheer luck that Martin spotted it in time to avoid getting too close to its output plume. He crawled up beside the tent, then rose into a squat, partly sheltered as he peered into the camp.

Just out of sight, a man spoke, his voice at the edge of patience as if he’d been repeating the same question for a while. ‘Are you a spy, or a thief? Which one is it?’

‘No!’ came Javeed’s plaintive reply. ‘I just wanted a job to feed the elephants.’

Another man laughed. ‘Do you see any elephants?’

‘No, but you could take me to Lavosestan.’

‘Where?’

The first man said, ‘He’s a crazy little thief. Do you know what we do to thieves who don’t tell the truth?’

‘I’m not a thief!’ Javeed retorted. ‘I’d never take anything – unless someone told me to.’

‘Really? So what were you planning to take? And who is your master who told you to take it?’

‘No one!’ Javeed insisted. ‘I just wanted to see the elephants.’

Martin forced himself to keep some perspective. Javeed wasn’t having an easy time with his captors, but he didn’t sound desperate yet. His priorities were not hard to guess: an attempted rescue that blew their whole mission would not be acceptable.

Martin crept into the camp, steering clear of the interrogators, hoping he hadn’t become disoriented and really was heading south. He wasn’t sure why there were so few people around; maybe they’d already sent a search party into the city, looking for Zal after he’d failed to return from his latest night of passion. The whole arrest scenario had been cooked up last weekend by the game’s software; the original story of Zal and Rudabeh had been a mixture of politics, family obligations and romantic swooning, loaded with proto-Shakespearean possibilities, but of limited interest to a six-year-old.

Helpfully, Zal’s tent was distinctly more ornate than the others; Martin could have sworn there was real gold thread in the design, or at least… whatever. A reddish-brown stallion was tied up right by the entrance; it regarded Martin irritably, and as he tried to squeeze past it, it began to neigh. Martin put a hand on its flank. ‘Sssh. Stay cool, buddy, and you might get to play Rakhsh in the sequel.’ That promise seemed to do the trick, or maybe it had caught a trace of its master’s scent on the intruder and deduced that Martin was here with Zal’s blessing.

He ducked into the tent. The silk brocade and khatam knickknacks were almost enough to blind a non-princely eye, but Martin scrabbled around beside the sleeping mat until the plain brown bag materialised from the clutter as a kind of absence of decoration that refused to go away. It was about the size of his hand, sealed with a knotted drawstring; it made no sound when Martin shook it, and when he squeezed it gently he felt nothing but a slight rearrangement of its contents beneath the material. Definitely not a dagger, nor lock-picking tools. Maybe a rolled-up piece of parchment?

Martin lifted his kameez and stuffed the bag down the front of his shalwar. The fabric bulged slightly, but the kameez would hide that. Whatever cultural specifics might plausibly be ascribed to this mutated version of a mediaeval poet’s tale of a much earlier time, Martin was fairly sure that the game’s rating precluded anyone patting down his groin.

The stallion snorted haughtily as he emerged from the tent, not quite betraying him, but making it clear that he was there only on sufferance. He moved quietly back the way he’d come, glad now of the mud on his clothes.

Then he stood at the edge of the river and bellowed, ‘Javeed! Pesaram! Koja’i?’

The reply came back instantly: happy, relieved, not quite tearful. ‘Baba! Inja hastam! Inja bia!’

Martin strode towards his son’s voice, oblivious to everything else around him, barely noticing the member of Zal’s retinue approaching him before the man stepped directly into his path.

‘Who are you?’

‘Forgive me, sir; I’ve been searching for my son.’ Martin looked past his interlocutor; Javeed was standing on a patch of bare ground between two men. One of them had a scimitar in a scabbard strapped to his back; Martin’s skin tingled with fear and revulsion, but he had to trust the game to have kept the threat abstract and muted. If anyone had waved a blade in Javeed’s face-

‘That’s not an answer.’

Martin forced himself to focus on the man blocking his way. ‘We were in the river, fishing; our boat struck a rock and went down. My son and I became separated. I swear, until now I was afraid he’d drowned.’

The man regarded him suspiciously, but a flicker of compassion crossed his face. Martin was sure he wasn’t human, but he wondered if he was one of the new-style Proxies that Nasim had mentioned, boosted with fragments of neural circuitry. Are you a dumb cousin of the thing I’ll leave behind? Martin wondered. Just human enough to react with real emotion to the idea of a drowned child?