The girls had been sound asleep for a long time, when Gwethyn was suddenly disturbed by an uneasy whimper from Tony. Wideawake in a moment, she sat up.
"What's the matter, my precious?"
The room was in complete darkness, but she could tell from the dog's warning growl that he was all on the alert.
"Do you hear anything?"
Tony's low grumble was a sufficient answer in his own language.
"Is it rats?"
"Be quiet, Gwethyn, and let us listen too," said Katrine, who was also aroused. "I thought I heard a queer noise."
In dead silence the girls waited. For a minute or two all was still, then came a curious subdued sound like the very gentle working backwards and forwards of a file.
"What is it?" whispered Gwethyn.
"I don't know."