That one opened onto a flight of rickety wooden stairs. Sophie heard someone move up there and shut the door hurriedly. It seemed only to lead to a sort of loft anyway. She hobbled to the next door. By now she was moving quite easily. She was a hale old woman, as she had discovered yesterday.

The third door opened onto a poky backyard with high brick walls. It contained a big stack of logs, and higgledy-piggledy heaps of what seemed to be scrap iron, wheels, buckets, metal sheeting, wire, mounded almost to the tops of the walls. Sophie shut that door too, rather puzzled, because it did not seem to match the castle at all. There was no castle to be seen above the brick walls. They ended at the sky. Sophie could only think that this part was round the side where the invisible wall had stopped her the night before.

She opened the fourth door and it was just a broom cupboard, with two fine but dusty velvet cloaks hanging on the brooms. Sophie shut it again, slowly. The only other door was in the wall with the window, and that was the door she had come in by last night. She hobbled over and cautiously opened that.

She stood for a moment looking out at a slowly moving view of the hills, watching heather slide past underneath the door, feeling the wind blow her wispy hair, and listening to the rumble and grind of the big black stones as the castle moved. Then she shut the door and went to the window. And there was the seaport town again. It was no picture. A woman had opened a door opposite and was sweeping dust into the street. Behind that house a grayish canvas sail was going up a mast in brisk jerks, disturbing a flock of seagulls into flying round and round against the glimmering sea.

“I don’t understand,” Sophie told the human skull. Then, because the fire looked almost out, she went and put on a couple of logs and raked away some of the ash.

Green flames climbed between the logs, small and curly, and shot up into a long blue face with flaming green hair. “Good morning,” said the fire demon. “Don’t forget we have a bargain.”

So none of it was a dream. Sophie was not much given to crying, but she sat in the chair for quite a while staring at a blurred and sliding fire demon, and did not pay much attention to the sounds of Michael getting up, until she found him standing beside her, looking embarrassed and a little exasperated.

“You’re still here,” he said. “Is something the matter?”

Sophie sniffed. “I’m old,” she began.

But it was just as the Witch had said and the fire demon had guessed. Michael said cheerfully, “Well, it comes to us all in time. Would you like some breakfast?”

Sophie discovered she was a very hale old woman indeed. After only bread and cheese at lunchtime yesterday, she was ravenous. “Yes!” she said, and when Michael went to the closet in the wall, she sprang up and peered over his shoulder to see what there was to eat.