"Well, you'd better get rid of it right away," retorted Laura. "We don't want anything more to happen—especially when the boys are away."
This time Violet proved to be right. Something did happen. It was after dark, the boys had not yet got back from the village, and the girls were setting the table in the kitchen—they had never found the courage to eat in the gloomy dining-room—when Violet set a dish down on the table with a bang that made the girls start and look at her in surprise.
As for Violet, she was too scared to speak for a moment. Then she stammered out:
"The strange motor car!" she said, while Billie and Laura stared at her.
"I thought I heard it before—"
"Sh-h," cried Billie, and they listened, hardly daring to breathe.
There was the same strange humming sound that had so startled them on their first night in the house, only this time, instead of coming from a distance and passing by, the noise seemed to get louder, then softer, louder and softer, as if whatever it was were approaching and retreating at regular intervals.
At that moment Mrs. Gilligan came into the room, and the girls called to her to listen also.
"That?" she asked, with a little laugh. "Why that's an automobile of course," and started for the front door. "Only I must say it's behaving mighty queer."
But when they opened the door and looked out into the rocky road there was no sign of an automobile, and yet the humming sound still kept on.
As they listened, wide-eyed, the noise grew softer and softer and gradually died away in the distance.