Staffer laughed; and Elsie shuddered at his half-heard voice.
"I don't . . . do what you like . . . But make sure . . . know too much . . . both dangerous."
Elsie shrank down as Staffer rose and the light traveled along the wall, but the men crossed the floor and she heard a cupboard being opened. They were now near the hall door and she missed what they said; but she had heard enough and must escape before the stranger left by the window.
Stealing out of the greenhouse, she ran back, with her brain busily at work. Madge was waiting where she had left her. Together they crept up the back stairs and into Madge's room.
Elsie was very calm when at last she felt it safe to speak.
"They came to the door once. What did you hear?" she asked in a whisper.
"The wreck. About three hours. There before high water! It wasn't Staffer's voice."
Elsie pressed her arm, and, listening eagerly, they heard a stealthy footstep in the passage. Then the handle of Elsie's door shook, as if it had been touched, and there was silence.
They waited for a few minutes while Elsie thought quickly. The situation, though still obscure, was getting clearer. Andrew was interfering with something it was necessary that Williamson should do, and Staffer had told his visitor that he could stop him as he liked, but must make sure. There had been something horribly threatening in his laugh as he said that Andrew and Whitney knew too much. The visitor was to do what he had undertaken, about low water, near a wreck.
The question was: What had he undertaken?