‘They hanged my uncle in there,’ Behrouz said. ‘In eighty-eight.’

‘Jesus.’ Martin was floored; this was the first he’d heard of it.

‘I was only a kid, nobody told me much.’ As he spoke, Behrouz kept his gaze fixed on the ground. ‘But I heard my father and grandfather talking about it.’

‘Do you know why he was arrested?’ There’d been thousands of extra-judicial killings in 1988; no trials, just a formulaic interrogation on political and religious matters, with wrong answers leading to death.

‘He belonged to some kind of leftist group. They weren’t killing people, or blowing things up – just publishing pamphlets against the mullahs. Actually, he’d been conscripted into the army, he was in Tehran on leave when they arrested him. No one really knew for sure what had happened for about a year. Then my grandfather heard that he was buried in a mass grave in Khavaran Cemetery. He was twenty-two years old when they killed him.’

Martin said, ‘That’s fucked.’ No wonder the place cast a pall over him. ‘Look, if you want to get out of here-’

Behrouz shook his head. ‘I can do my job. I’m only telling you so you’ll stop asking me that.’

‘Okay.’ Martin got it now. ‘I’ll shut up about it, and we’ll both just do our jobs.’

‘Good.’

As they walked on, Martin felt a surge of anger, but there was nothing to be done with it; the last thing Behrouz needed was to hear him ranting against tyrants.

‘So if I’m hooked on Iranian cuisine,’ he said, ‘where exactly does a middle-aged, atheist foreigner start looking for an Iranian wife?’

Behrouz said, ‘Outside the divorce courts.’

Martin woke from shallow, unquiet sleep to the sound of helicopters approaching. He staggered to his feet, reluctant for a moment to let the blanket he was wrapped in drop from his shoulders. The sound was coming from the direction of the prison, and it was accompanied by spotlight beams sweeping across the park; he counted six before one of them struck his eyes, blinding him to any more detail.

He crouched down and shook Behrouz awake. People were already gathering around the park’s scattered trees; there was no sign of the kind of panic that would have ensued if anyone had actually seen a gun mounted behind one of the spotlights, and a part of Martin still refused to believe that the government would slaughter its own people en masse – even in 1988 they’d gone through an elaborate inquisitorial ritual, not just fired into an unarmed crowd – but what if they strafed the park lightly and killed a dozen protesters out of the thousands? Were they prepared to sell that, politically, as a necessary trade-off for the sake of restoring order? Were they ready to call the bluff of the majority of Iranians who’d stayed out of the fray so far, and say: choose us – with a few unavoidable casualties – or back the traitors, and blame only yourselves when the streets are running with blood?

Martin joined the huddle of bodies in the shadow of the nearest tree. Under the circumstances, the whole idea of shelter was marginal, but anything was better than standing beneath a spotlight on open ground. He glanced at Behrouz, who was ashen; Martin knew better now than to offer any solicitous remarks, but he couldn’t help feeling a twinge of guilt at the disparity between them. Though he was far from nonchalant about the situation himself, he was certain that if he’d had a young family it would have been ten times harder to be here.

As the minutes passed, it became clear that this operation was not a simple aerial assault on the protesters. The spotlights remained trained on the park, but the helicopters were keeping their distance and showing no signs of dispensing anything unpleasant: no bullets, no tear-gas, not even a blast of pressurised water.

The dazzle of the beams made it hard to keep watching the airspace over the prison, but Martin noticed a subtle shift in the illumination on the ground; the lights bathing the immediate area hadn’t changed, but an adjacent region of the park had become darker. It took him a few seconds to make sense of that.

He turned to Behrouz. ‘I think one of them just landed inside the prison.’

‘Yeah.’

‘Meaning what?’

There was some angry shouting, and Martin saw people breaking cover and running across the grass to confer. Behrouz said, ‘I don’t know what it means, but they think the prison’s being evacuated.’

‘Okay.’ Martin considered this hypothesis. Anything was better than a hail of bullets, and maybe two could play the game of frustrating your enemy without bloodshed. There were plenty of inaccessible prisons out in the countryside – and even if they were full, it would have taken the government only a few days to assemble desert camps of huts ringed with razor-wire. If they plucked everyone out of Evin and deposited them in unknown or hard-to-reach locations, the siege would be deflated into an irrelevant farce.

Behrouz nudged him. ‘Look.’ Four men had picked up one of the concrete benches that were scattered throughout the park and were carrying it over their heads like an upside-down canoe. Martin supposed the concrete might offer a degree of protection from descending gunfire… but any safety advantages would be negated by the fact that the men were marching straight towards the prison itself.

When they passed out of sight behind a tree, Behrouz rose to his feet. ‘Come on.’

Martin’s skin turned to ice. ‘Are you crazy?’

‘We don’t have to get too close, but we should keep them in sight.’

For one uncharitable moment Martin wondered if Behrouz was just trying to outdo him in the bravado stakes – as if the mere suggestion that he might have wanted to rejoin his family had wounded his pride. But that was unfair; what he was proposing was reasonable. Martin stood and followed him, zigzagging across the grass from tree to tree, wondering what an observer from above would make of them scuttling along in the wake of the concrete canoeists.

They stopped at the corner of the park; they had a tree to themselves and a clear view of the road that ran past the park and alongside the prison’s perimeter wall. The men with the bench were already in front of the prison, twenty or so metres away. The wall itself blocked the line of fire from the watchtowers, but one of the helicopters was hovering directly above the prison gates. Martin couldn’t imagine what the men’s purpose was – unless they planned to use the bench as a battering ram, and he couldn’t see that ending well.

Before the men reached the gates they stopped and rid themselves of the bench, depositing it on the ground in an upturned V. Then they turned and walked back towards the park.

‘I don’t get it,’ Martin confessed. ‘Do they think the prisoners are going to be moved by truck?’

Behrouz said, ‘The general population’s about fifteen thousand, but even the thousand or so politicals would take an awful lot of helicopter trips. So maybe the helicopters are for the top brass, and the grunts and the prisoners will go by truck.’

‘Okay, but how is a park bench going to slow them down?’

Behrouz spread his hands; he had no idea.

Now that he was out of the direct glare of the spotlights, Martin could see the placement of the helicopters more clearly. Along with the one hovering above the gate, there were four lined up in a queue that stretched eastwards from the far side of the prison. As he watched, a sixth helicopter rose into sight and flew north, up along the slope of the mountains. Then the first in the remaining queue of four approached and descended inside the prison walls. It was like a taxi rank.

Another two groups of men came down the road, carrying two more benches from the park. Martin wasn’t sure how many benches there were in total, but perhaps a large enough pile of them would constitute more than a trivial nuisance that could be moved aside in seconds. As they approached the prison gate there was a burst of automatic gunfire from the helicopter standing sentry; Martin flinched and the men stopped walking, but nobody appeared to have been hit.