It was dreadfully unlike anything a grown.up would be expected to do. Polly’s heart came into her mouth， and she and Digory started backing towards the little door they had come in by. Uncle Andrew was too quick for them. He got behind them and shut that door too and stood in front of it. Then he rubbed his hands and made his knuckles crack. He had very long， beautifully white， fingers.
“I am delighted to see you，” he said. “Two children are just what I wanted.”
“Please， Mr Ketterley，” said Polly. “It‘s nearly my dinner time and I’ve got to go home. Will you let us out， please？”
“Not just yet，” said Uncle Andrew. “This is too good an opportunity to miss. I wanted two children. You see， I‘m in the middle of a great experiment. I’ve tried it on a guinea.pig and it seemed to work. But then a guinea.pig can‘t tell you anything. And you can’t explain to it how to come back.”
“Look here， Uncle Andrew，” said Digory， “it really is dinner time and they‘ll be looking for us in a moment. You must let us out.”
“Must？” said Uncle Andrew.
Digory and Polly glanced at one another. They dared not say anything， but the glances meant “Isn’t this dreadful？” and “We must humour him.”