“And you may expect us early in the afternoon. I have myself some small business matters to attend to. Will you not wait and breakfast?”

“No, I must go. My heart is lightened already since I have confided my trouble to you. I shall look forward to seeing you again this afternoon.” She dropped her thick black veil over her face and glided from the room.

“And what do you think of it all, Watson?” asked Sherlock Holmes, leaning back in his chair.

“It seems to me to be a most dark and sinister business.”

“Dark enough and sinister enough.”

“Yet if the lady is correct in saying that the flooring and walls are sound, and that the door, window, and chimney are impassable, then her sister must have been undoubtedly alone when she met her mysterious end.”

“What becomes, then, of these nocturnal whistles, and what of the very peculiar words of the dying woman?”