I bring the teapot out into the sitting room, which is now bathed in amber sunlight from the west.

‘Do you really think this Meera could help me? She’s probably super busy.’

O sighs. ‘I don’t know, darling. She certainly can’t help you if you don’t approach her.’

We sip our tea, O using her good hand. She’s thinking hard. I know because she frowns more than usual when she’s concentrating. The frown isn’t as deep as her debugging-code frown but it’s deeper than her reading-novels-in-their-original-Russian scowl.

Finally, she says, ‘Well, this is crazy, but.’

I put my hands over my face. Whenever O says, ‘This is crazy, but—’ it means either she wants to do something slightly illegal (usually involving motorbike stunts), or she’s going to send me to the British Library to do research on a crazy theory. Like her hypothesis that the Incas invented quantum chromodynamics diagrams before Richard Feynman. Or that bear meat cures lung cancer. Don’t get me wrong – O’s brilliant at IT, but she’s got a flamboyant streak and an ego roughly the size of Greenland (as it appears on a map). Whenever she says, This is crazy, but, or, I’m sure I’m wrong about this, I just know it’s kicking off.

I watch her cup shake in her hand. I wish she didn’t have to be so old, and I wish she weren’t ill. I feel a mad affection for her, even if I’m not certain it’s mutual.

‘I’m sure I’m wrong about this.’

You see? She’s said them both. Here we go.

‘It’s just that, looking at their work, knowing that they are surely able to induce certain kinds of brainwaves, then they might be able to tamper with dreams.’

‘Using nanotech? That’s a thing? How?’

‘I don’t know.’ She won’t look at me.

‘Come on, O. Loads of drugs affect your dreams. My uncle took something for dementia and it gave him horrible nightmares. Or how about Daphne, for that matter.’

O’s sister has dementia, but O doesn’t like talking about it so she ignores my remark.

‘If the treatment works with AR, then control could be a possibility,’ O tells me. ‘Using live imaging alongside a BigSky database of millions of brainwave samples correlated with subjective experience. One could add nano-delivered agents implanted in the body with the ability to operate on brain tissue to rebuild, or to build anew. Have you seen the work on remyelination done by nano-engines?’

‘No, I haven’t, because I’m being manipulated by BigSky and their sinister mind-control programme. Must. Buy. Apps.’

I stick my arms out in front of me like a mummy in a Carry On film and shamble around the flat. She isn’t laughing. Not even a little smile. Wow, she hates BigSky. So I give up joking with a sigh, and (a little sarcastically) I recite the words I know she wants me to say:

‘That sounds sinister, O. Is there any science for that?’

‘I just said. Remyelination. Look it up. But you must understand this much, darling: some of these nanotech guys aren’t scientists in the highbrow Ivory Tower sense of the word. They’re engineers, some of them self-taught. You know, the days of Big Science mean that the Victorian scientist who pottered in his shed may be long extinct, but a new subclass has sprung up in the last ten years.’