I listened but I heard nothing.

“Don’t you hear it?” he gasped, and he pointed upward.

“Upstairs?” I stammered. “Is there somebody upstairs?”

I strained my ears, and at last I fancied I could hear a fugitive sound like the light tapping of footsteps.

“It must be somebody walking about up there,” I suggested.

But at these words Arthur seemed to stiffen. The excitement died out of his face.

“No!” he cried in a sharp rasping voice. “No! It is nobody walking about up there!”

And he fled into his room.

For a long time I lay trembling, afraid to move. But at last, fearing for Arthur, I got up and crept to his door. He was lying on the couch, with his face in the moonlight, apparently asleep.