‘The hotel was mad and unforgiving!’ I said at once, because this was something else that had been passing through my mind as we drove along. I gave vent to my feelings. ‘They charged me a pile of money, and I didn’t understand why. When I asked for an explanation the receptionist told me I should have read a booklet in the room. The only warnings I saw were opaque, and the cost of the penalties was undefined.’

I had been wondering privately about trying to find out who owned or managed the hotel, and sending some kind of protest to them. However, the unexpected and profitable refund of the train fare had taken the urgent edge off that need.

‘It’s not the hotel’s fault,’ Frejah said. ‘Dealing with mutability is a problem for everyone, but it’s worst of all in the south. Every home and office has to take similar precautions. It’s more acute in a big hotel like the Plaza. Because they take in visitors from islands all over the world, people like you, their infrastructure is much more vulnerable. They have to account for everything that happens.’

‘Well, their warnings are not clear. I accidentally used the wrong key—’

‘It happens in hotels all the time. Late at night, dimly lit corridors, people leaving the bar, in a hurry to get back into their rooms for whatever reason. Wrong key goes in. Easily done—’

‘It sounds familiar,’ I said, remembering my erratic meandering back to my room. ‘Maybe they shouldn’t give everyone two keys.’

‘Well, they have to. But if several people make the same mistake at the same time the whole building can be immobilized. That’s difficult to fix, and expensive.’

‘I had no idea what the risks were, or even what was happening. Why do they hand out those keys if they can cause so much trouble?’

‘It’s a safety law. Used properly the key can’t do any damage. You were assumed to know what to do, or at least that you would have read the information in the room.’

‘I was hardly in the room. I didn’t have time to take it all in.’

‘Then I suppose you could say that’s the reason for the surcharge. You’ll be certain not to do it again.’

‘It sounds like the Dearth penal code,’ I said. ‘Deterrence for others.’

‘You might be right. We hand out a lot of fines.’

‘I still don’t know what mutability is.’

‘I’m not the person to tell you.’

‘You’re the only one I can ask,’ I said.