"Listen!" said Cicely, with a start.
It was the same strange sound again which they had heard on their former expedition—a low, long-drawn-out moaning, as of someone in pain, feeble at first, then growing louder, and suddenly ceasing.
"Oh! I wonder if she's hurting anybody?" cried Cicely, shuddering with horror.
"I'd give a great deal to find out what's going on. I'm afraid it's something that won't bear the light of day," said Lindsay uneasily.
"Dare we wait till she comes out of her hiding-place?"
"Yes, but we mustn't stay here. It would spoil everything if she caught us. Let us go outside and close the door again, and watch through the keyhole; then, if we see her coming, we can rush."
Mrs. Wilson's errand was evidently a long one. Though they relieved each other more than once in mounting guard over the keyhole, she did not return.
"Perhaps she knows we're here, and won't come out till we've gone," suggested Lindsay at last.
"How could she know?"
"She may have been looking at us all the time through some little spy place."