"At this instant a horrible change came over his expression; his eyes stared wildly, his jaw dropped, and he yelled in a voice which I can never forget, 'Keep him out! For Christ's sake keep him out!' We both stared round at the window behind us upon which his gaze was fixed. A face was looking in at us out of the darkness. We could see the whitening of the nose where it was pressed against the glass. It was a bearded, hairy face, with wild cruel eyes and an expression of concentrated malevolence. My brother and I rushed towards the window, but the man was gone. When we returned to my father his head had dropped and his pulse had ceased to beat.
"We searched the garden that night but found no sign of the intruder save that just under the window a single footmark was visible in the flower-bed. But for that one trace, we might have thought that our imaginations had conjured up that wild, fierce face. We soon, however, had another and a more striking proof that there were secret agencies at work all round us. The window of my father's room was found open in the morning, his cup– boards and boxes had been rifled, and upon his chest was fixed a torn piece of paper with the words 'The sign of the four' scrawled across it.