Another phrase/sentence I don't understand from Narnia Book 1 Magician's Nephew:
Digory was quite speechless, for Uncle Andrew looked a thousand times more alarming than he had ever looked before. Polly was not so frightened yet; but she soon was. For the very first thing Uncle Andrew did was to walk across to the door of the room, shut it, and turn the key in the lock. Then he turned round, fixed the children with his bright eyes, and smiled, showing all his teeth.
"There!" he said. "Now my fool of a sister can't get at you!"
Don't understand completely. I understand every word, but I don't know what he is talking about.