‘So what do you think?’ Josie asked with anxious eyes.

‘It’s okay,’ the Mother said. ‘It’ll be okay. Paul, you want to see it, go ahead.’

‘Maybe in just a minute,’ the Father said. ‘Capaldi, I’d appreciate you getting finished with us quickly today. I want to take Josie out for a coffee and cake.’

‘That’s okay, Paul. We have everything under control. You sure you’re okay there, Chrissie?’

‘I’m fine,’ the Mother said, but she hurried to reach the black sofa.

‘Josie,’ Mr Capaldi said. ‘Just before we do this, what I’d really like is for Klara here to do me a little favor. I have a small assignment for her. I was thinking maybe she could be getting on with it while we took our photos. That okay?’

‘Fine by me,’ Josie said. ‘But you should ask Klara.’

But Mr Capaldi now addressed the Father. ‘Paul, maybe as a fellow scientist, you’ll agree with me. I believe AFs have so much more to give us than we currently appreciate. We shouldn’t fear their intellectual powers. We should learn from them. AFs have so much to teach us.’

‘I was an engineer, never a scientist. I think you know that. In any case, AFs were never in my territory.’

Mr Capaldi shrugged, and raising a hand to his beard, appeared to be checking its texture. Then he turned to me, saying: ‘Klara, I’ve been devising a survey for you. A kind of questionnaire. It’s up there on the screen ready to go. If you wouldn’t mind completing it, I’d be so grateful.’

Before I could say anything, the Mother said: ‘It’s a good idea, Klara. Give you something to do while Josie gets through her sitting.’

‘Of course. I’d be happy to help.’

‘Thanks! It’s nothing difficult, I swear. In fact, what I’d like, Klara, is for you to make no special effort. The whole thing works best if you respond spontaneously.’

‘I understand.’

‘They’re not even questions as such. But why don’t we just go up there and I’ll show you? Folks, Josie, this won’t take a minute. I’ll get Klara settled, then come right back down. Josie, you look so well today. This way, Klara.’

I thought he might take me also to the Purple Door, but we went to the opposite side of the room, where a different metal staircase climbed to its own section of balcony. Mr Capaldi went first up the steps, then I followed, taking each step carefully. When I glanced back down, I saw Josie, the Mother and the Father looking up at us, the Mother still seated on the black sofa. I waved towards Josie, but no one below moved. Then Josie called up: ‘Be good, Klara!’

‘This way please, Klara.’ The balcony was narrow, made from the same dark metal as the staircase. Mr Capaldi was holding open a glass door leading into a room smaller even than Josie’s en suite, dominated by a padded desk chair facing a screen. ‘Please sit down in there. It’s all waiting for you.’

I seated myself with a white wall at my shoulder. Beneath the screen was a narrow ledge offering three control devices.

The room wasn’t large enough for Mr Capaldi to come in too, so the glass door remained open while he gave me his instructions, reaching over sometimes to manipulate the devices. I listened to him carefully, even though I became aware that below, the Mother and the Father were once again using tense voices. Behind Mr Capaldi’s words, I heard the Mother saying: ‘No one’s insisting you stay, Paul.’

‘It’s not consistent,’ the Father was saying. ‘I’m merely pointing out the inconsistency.’

‘I’m not trying to be consistent. I’m just trying to find a way forward for us. Why make it harder than it is, Paul?’

Beside me, Mr Capaldi laughed, broke off from his instructions and said: ‘Oh my. Looks like I’d better go down there and referee! You all straight here, Klara?’

‘Thank you. Everything’s quite clear.’

‘I appreciate it. Anything puzzles you, please call down.’

When he closed the door it actually nudged my shoulder, but I could see sufficiently through its glass to watch Mr Capaldi descending beneath the balcony level. Then I allowed my gaze to go beyond, across the empty air, over to the opposite balcony and the Purple Door from which the Mother had recently emerged.

I began Mr Capaldi’s questionnaire. Sometimes a question would come on the screen as writing. At other times there were shifting diagrams, or the screen would darken and sounds with many layers emerge from the speakers. A face – Josie’s, the Mother’s, a stranger’s – would appear then vanish. At first, short responses of around twelve digits and symbols were appropriate, but as the questions grew more complex, I found myself giving longer answers, some running to over a hundred digits and symbols. All the time, the voices from below remained tense, but with the glass door closed, I could no longer hear their words.

Halfway through my assignment, I caught movement through the glass and saw on the opposite balcony Mr Capaldi leading the Father up onto it. I continued my assignment, but having grasped its central purpose, I no longer needed to give it much attention, and was able to watch the Father, nervously drawing the raincoat around him, approaching the Purple Door. He had his back to me and I was looking through frosted glass, so I couldn’t be sure, but he looked as though he’d become suddenly ill.

But Mr Capaldi, on the balcony beside him, seemed unconcerned, smiling and talking cheerfully. Then he reached up to the keypad beside the Purple Door. From inside my cubicle I couldn’t hear the unlocking hum, but the next time I glanced their way, the Father had gone inside and Mr Capaldi was leaning in through the doorway, saying something. Then I saw Mr Capaldi move suddenly backward, and the Father came out and, though I couldn’t be sure through the frosted glass, he looked no longer ill but filled with a new energy. He seemed not to mind that he’d almost knocked Mr Capaldi aside, and started down the metal steps at reckless speed. Mr Capaldi, watching him, shook his head as a parent would do when a child has a tantrum in a store, then closed the Purple Door.

The images on the screen were changing ever faster now, but my tasks remained obvious, and after several minutes, without losing focus, I pushed partially ajar the glass door beside me. I could then hear more clearly the voices below.

‘What you’re emphasizing here, Paul,’ Mr Capaldi was saying, ‘is how any work we do brands us. That’s your point, am I right? It brands us, and sometimes brands us unjustly.’

‘That’s a very smart way of misunderstanding my point, Capaldi.’

‘Paul, come on,’ the Mother said.

‘I’m sorry, Capaldi, if this sounds impolite. But frankly? I think you’re deliberately misconstruing what I’m saying.’