‘You won’t have any problems, Dr Fremde. All the elevators have printed notices reminding you what to do in an emergency. This is a period of vertical stability, so none of that will apply to you tonight. On the other hand, as this is your first time I have to inform you about mutability arrangements. I notice you are a citizen serf of the seigniory of Salay?’

‘Yes,’ I said, wondering how much longer this would take. I was anxious to go up to my room, take a shower, and so on.

A second electronic card had appeared in his hand and he was sliding it across to me. It was the same size and shape as the other one, looked slightly thicker, and was white all over with a bright red border. A computer chip was embedded close to one edge. Apart from a hotel logo, nothing was printed on the card itself.

‘Again, you are unlikely to need this card tonight but the hotel rules insist you carry it at all times. Mutability is a problem many people who visit Dearth have never experienced before, but while you are staying at the Plaza Hotel we ask that you treat it with great seriousness so that you will fully enjoy your stay.’

‘What exactly do you mean by mutability?’ I said.

‘You’ll find all the information you need in your room. Always use the standard room key. That is the one for locking and unlocking your door.’ He started speaking more quickly and insistently, as if he had recited the same words many times before. ‘Under seignioral mutability regulations we have a legal requirement to provide you with a second key. This will also open your door, or any other to which you are directed. You must only use the second key if the first does not work properly. Hotel management are always on hand, here in Reception at street level, or in any of the Mutability Stations. There is a Mutability Station on every floor of the hotel. If you experience any difficulties at all, you can always find someone to help you. Both keys must be returned to Reception before you leave the hotel.’

‘It sounds terrifying,’ I said, trying to get an informal, unrehearsed response from him.

‘A routine, sir,’ he said. ‘The last mutability crisis in this hotel was seventeen years ago – I had just started school. The incidence level is currently flagged at green. I hope you will have a most pleasant stay.’

The young receptionist turned away from me with a professional smile, to greet two more arriving guests. They were crossing the lobby with a slow walk, as thickly wrapped as I was. The man and the woman pushed up their protective eye-glasses, revealing their red-rimmed eyes and their eyebrows whitened by frost. As they passed me I felt the deep chill of the outside air still clinging to them.