The flat is in a modern building, very white and sheer and not what she was expecting. She walks up four floors and along a pale, honey-carpeted corridor to find the door she is looking for. It is high-gloss black, the number printed hugely under the lacquer and repeating itself up and down the panel in regressing indigo and blue shadows. She knocks rather than ringing the bell, and then waits, because it’s the middle of the night.