Eventually, I said: ‘So is the bulge still there? Couldn’t it be geologically investigated, explained?’

‘The bulge is not there. It was caused by mutability. It was a real event, witnessed and recorded, but afterwards most people seemed to doubt it had happened at all.’

‘What about the victims?’ I said. ‘The people you said were reportedly killed. Was that imaginary?’

‘They died. Their identities are known. Two of them were from Dearth City; the third was a visitor from one of the other islands. The avalanche was a real event, but the cause of it is in doubt. Now, a month later, most people accept that it was imagined.’

‘Mutability can change physical dimensions? I can’t believe that.’

‘Nor can most people here. We have to live with the phenomenon.’

‘All this is new to me – I had never heard of mutability until yesterday.’

‘You told me you’re from the Salay Group?’

‘Salay Raba, yes.’

‘Salay’s an interesting case. According to the mutability experts Dearth is not the only island that experiences the phenomenon. There are thought to be between two and three hundred islands in other parts of the Archipelago where there are gravitational anomalies. The vast majority of islands are unaffected.’ Frejah was driving noticeably more slowly as we talked about this. The engine was making a distinctive back-burning hunting sound as we gradually decelerated. ‘But there are a few islands, several hundred, which are described as potentially vulnerable. They are classified as Mutably Incipient. Some islands in Salay are included in that. Salay Raba is one of them. In fact at a high level.’

‘I’ve lived on Raba all my life. I’ve never experienced anything like it, never heard about it and I don’t know anyone who has.’

‘I was born on Salay Hames, the fifth. That’s even higher on the scale of incipience, but until I moved to Dearth as a kid I’d never known it either.’

Again I was silent, trying to work out what to believe, and how much of it. I glanced at my wristwatch, moving normally – it was an hour or so since I had last looked, and it was showing what felt subjectively still the correct time. The tiny digital clock on Frejah’s dash confirmed it. Mutability affected even the flow of time on this island? Somehow that was easier to believe than that a mountain could temporarily produce millions of tonnes of bulge – but isn’t time also immutable, an absolute? If that was so, then it must be the clocks, the chronometers, the cellphones, which drifted away from true?