I heard the sound too—­a sound like a light footstep following us.

“No matter who it is, or what it is,” I said, “let us walk on.  In another minute, if there is anything to alarm us, we shall be near enough to the house to be heard.”

We went on quickly—­so quickly, that Laura was breathless by the time we were nearly through the plantation, and within sight of the lighted windows.

I waited a moment to give her breathing-time.  Just as we were about to proceed she stopped me again, and signed to me with her hand to listen once more.  We both heard distinctly a long, heavy sigh behind us, in the black depths of the trees.

“Who’s there?” I called out.

There was no answer.

“Who’s there?” I repeated.

An instant of silence followed, and then we heard the light fall of the footsteps again, fainter and fainter—­sinking away into the darkness—­sinking, sinking, sinking—­till they were lost in the silence.

We hurried out from the trees to the open lawn beyond crossed it rapidly, and without another word passing between us, reached the house.

In the light of the hall-lamp Laura looked at me, with white cheeks and startled eyes.

“I am half dead with fear,” she said.  “Who could it have been?”

“We will try to guess to-morrow,” I replied.  “In the meantime say nothing to any one of what we have heard and seen.”

“Why not?”

“Because silence is safe, and we have need of safety in this house.”

I sent Laura upstairs immediately, waited a minute to take off my hat and put my hair smooth, and then went at once to make my first investigations in the library, on pretence of searching for a book.

There sat the Count, filling out the largest easy-chair in the house, smoking and reading calmly, with his feet on an ottoman, his cravat across his knees, and his shirt collar wide open.  And there sat Madame Fosco, like a quiet child, on a stool by his side, making cigarettes.  Neither husband nor wife could, by any possibility, have been out late that evening, and have just got back to the house in a hurry.  I felt that my object in visiting the library was answered the moment I set eyes on them.

Count Fosco rose in polite confusion and tied his cravat on when I entered the room.

“Pray don’t let me disturb you,” I said.  “I have only come here to get a book.”

“All unfortunate men of my size suffer from the heat,” said the Count, refreshing himself gravely with a large green fan.  “I wish I could change places with my excellent wife.  She is as cool at this moment as a fish in the pond outside.”

The Countess allowed herself to thaw under the influence of her husband’s quaint comparison.  “I am never warm, Miss Halcombe,” she remarked, with the modest air of a woman who was confessing to one of her own merits.

“Have you and Lady Glyde been out this evening?” asked the Count, while I was taking a book from the shelves to preserve appearances.