The train arrives. I’m finding it hard to shake off the paranoia induced by our game. From where I’m sitting I have a good clear view of six people. A harassed, gimlet-faced woman in a sari. Her bespectacled daughter. A young builder with tattoos who seems determined to sit with his legs as wide apart as possible, as though he were about to give birth. A man whose white facial hair, busy shirt, red-threaded tweed jacket, black boots and expensive retro wristwatch combine in such a messy and confusing way, I’d never be able to identify him in a line-up. Two animated African tourists trying to swap something from one mobile phone to another.

Of these, Glasses Girl, Clown Man and Legs Akimbo have allowed their attention to be snatched away. The girl’s glasses are cheap half-silvered jobs, and from the flickering petrol-sheen smothering her eyes I can just about identify which space-opera she’s watching. The other two are a scarier proposition, their pupils and irises silvered behind active contact lenses. These lenses are probably not AR-enabled, because the men’s heads are too still, absorbed in some reasonably static immersive environment. They’re reading, or more likely watching. Legs’s thumbs are twitching but they’re bare and clean, free of any shiny trail of conductive gel, so his movements are more likely a tic, rather than virtual keypresses.

It shouldn’t be such an effort, seeing what strangers are up to on a train. My heart shouldn’t still be racing, as it’s racing now. The game is over, but it seems to me it’s been replaced, not with any sense of the normal, but with another, creepier, more insidious game.

Ten minutes later I change trains for a more direct service, underground at first, then elevated, that stitches a path round suburban hills, up to and through the highest of the city’s ring of mountains. The city sprawls here because the valley soil is mostly sand. Any building above four storeys tends to keel over – a fact learned the hard way by ambitious ecclesiastical architects hundreds of years ago. All the really tall buildings – the high-rise blocks and the most ancient cathedrals – are built upon the rock outcrops that rise from the flat valley floor like teeth in a gum. The hills are called islands. Isle of This, Isle of That. The coincidence wasn’t lost on Michel, whose game bible climaxes with the city inundated by a rising flood, skinned with burning petrol. This is pure fantasy. We are too far inland for an inundation.

My phone rings.

‘Where are you?’

‘I’m running late.’

‘Are you on the train?’

‘Yes.’

‘How far from the stop are you?’

‘About a minute.’ The train is already throttling down.

‘I’ll wait for you.’

‘Cheers, Ralf.’

This evening – and for the first time ever – Ralf chooses the restaurant. Its walls are hung with antique plates, white with multicoloured designs. The proprietress tells us about them – how all the colours come from a single pigment. How you won’t find these plates produced anywhere outside the Levant. It is a quaint assertion, as though her little restaurant could have somehow sidestepped centuries of relentless globalisation.

‘Don’t knock it till you’ve tasted the food.’

‘I’m not knocking anything.’ How strange, though, to be following Ralf’s recommendation.

‘Is Michel coming to this party, do you know?’ Ralf is a fan of Michel’s books. He has a full set of slipcased hardbacks, signed. It’s one of the reasons Loophole has fallen further and further under the spell of Bryon Vaux. Michel’s books are the source material for Vaux’s most lucrative film franchise, and Ralf has wanted to apply Loophole’s every technical innovation to better realise Michel’s world.

When Ralf heard that Michel was going to be writing our game bible, he was like a kid on his way to see Santa Claus. Sadly, Michel has proved every bit as elusive as the real Father Christmas, communicating with us only by written word. I don’t know whether this is just pressure of work, or some personal fall-out from Christmas.

Either way, Ralf is one disappointed fan.

‘Vaux will be there, I suppose.’

Ralf puffs himself up at that. Ralf, as Chief Imagineer, has met Bryon Vaux several times now. ‘I’ll introduce you,’ he says, as though this were a favour specially in his gift. There’s a pomposity comes over Ralf whenever he talks about Vaux. I used to find it touching, but now it has begun to irritate me. It’s not entirely Ralf’s fault. He is now, of necessity, one of the great producer’s gatekeepers. Every digital entrepreneur and failed screenwriter and wooden drama student wants a piece of him.

Our food arrives. Ralf sits back to make room for the proprietress. He has a paunch now. He’s going to have to watch that. I let him order for me, curious to discover what has so excited his retarded palate.

One bite and I’m flailing for the salep jug.

Ralf laughs. ‘You see?’

The salep, warm and creamy, gums round the fire in my throat like a retardant foam. My whole mouth sings. ‘What is this stuff?’

Ralf shrugs, pleased with himself for so surprising me. ‘It’s real çig köfte. There’s this spice in it called isot. A kind of black paprika.’

A minute later I’m recovered enough to dare another mouthful. And another. And another. I wish to God I hadn’t eaten earlier, this stuff is delicious. ‘How did you find this place?’

‘It’s one of Vaux’s haunts,’ Ralf says. ‘His local.’

‘Yes?’

‘He has a house near here.’

The menus come around again. I say, ‘They have a milk dessert on here called Chicken Breast. How does that work?’ It occurs to me that I have become Ralf.

Ralf pulls out his phone and checks the time. ‘We’d better settle up.’

The sun is low in the sky and, in the park, the young spring foliage shines like foil. The party is set up in the ornamental garden. Brick steps climb the hillside. Paths send out branches at precise, perpendicular angles. The effect is softened by all the planting wound round the trellises and gazebos: lilac and clematis, grapevine and rose. Come summer, there will be welcome shade here. This early in the year, it’s easy enough to find gaps in the screening foliage to enjoy the view. This evening the city, softened into butter by the sun, puddles around the blue paste jewel of the Middle.

Guests stand chatting in small, nervous groups among the stone seats, ornamental nooks, fountains and artful screens. Waiters in whites move among us with champagne and canapés.

‘Glasses on, people!’

And here he comes. Laughing. Glad-handing. Ralf turns and nudges me. I wince against the flashlight spraying and rippling through the leaves and through the crowd that gathers around us as people surge forward to grab their five-second shake-and-grin with our legendary host.

Sunlight catches in his shocked-white hair.

‘What’s the matter, Connie?’

His hair.

‘Bryon!’

Vaux knows Ralf’s voice. He turns.

There is something here I am missing. Something obvious and terrible.

‘Conrad’s here! You haven’t met. My business partner. Bryon!’

His face lights up, seeing Ralf among all these anonymous, uplifted faces. Photographers surround him, lighting him up like a poster. No army drab this time. A tux, and wrapround shades so shiny, featureless and deadly black, they might be a single piece of enamel.

Camera flash streaks across the big black lenses of his shades as he reaches out to shake my hand. A beat. ‘Conrad?’ He hesitates. Bryon Vaux. Producer of Michel’s Shaman franchise. Majority shareholder in Loophole.

‘Connie?’

The crowd carries him on. My hands hang limp and lifeless at my sides.

‘Conrad?’

I turn away to face the city, and pulling my wraprounds from my pocket, I let myself slip back into the game.

The city has been rendered down to a jumble of charcoal-grey plinths – stone footprints where building after building has been magicked away. At this distance only the biggest, most rectilinear footprints stand out. Most of the city is reduced to rubble. This is my home with its inner chaos exposed, no more now than a ghastly iteration of the same salt crystal. City as tumour. A spreading circle of dead tissue. City as leprosy. ‘Ralf. I’ve met him.’