I stared at him very blankly. The object of such a communication was difficult to imagine, and I knew of nothing incriminating in my possession, which might have tempted the assassin to lure me from the house whilst he obtained possession of it. In ever-growing excitement I watched the houses slipping behind us as we swept along. Then we came to the tree-lined expanse of road immediately leading to the cottage. As the car stopped, I leaped out quickly, Gatton close upon my heels, and ran up the path to the door. From certain indications with which I was familiar, I observed that Coates was out, whereby I concluded that he had set off to meet the mythical "man with a box." Not without apprehension I inserted the key in the lock and opened the door. As I did so, I beheld a most singular spectacle. The careful Coates had closed all the windows as usual before quitting the house, so that there was comparatively little draught along the corridor. But as the door swung open I perceived a sort of gray fog-like vapor floating over the carpet about a foot in depth and moving in slightly sinuous spirals upward towards the opened door! At this phenomenon I stared in speechless astonishment; for whilst it resembled steam or the early morning mist which one sometimes sees upon the grass in hot weather, I was wholly at a loss to account for its presence inside my cottage! "Good heavens!" cried Gatton, and grasped me by the arm with so strong a grip that I almost cried out. "_Look! Look!_" "What the devil is it?" I muttered; and turning, I stared into his face. "What _can_ it be?" "Stand back," he said strangely, and pulled me out into the porch. "Do you notice a peculiar smell?" "I do--a most foul and abominable smell." Gatton nodded grimly. "God knows what has happened here since you left," he said; "but of one thing I am sure--you must certainly bear a charmed life, Mr. Addison. There has been a third attempt at your removal!" This choking smell which now rose to my nostrils had in it something vaguely familiar, yet something which at that place and that time I found myself unable to identify; but: "We shall have to open the windows!" rapped Gatton. Suiting the action to the word, he took out his handkerchief, and holding it to his nostrils went running along the corridor, his feet oddly enveloped in that mysterious mist. A moment later I heard the bang of a swiftly raised window, then another, and: "Stand clear of the door!" called a muffled voice. A moment later Gatton came racing back again, coughing and choking because of the fumes which arose from that supernatural fog carpeting the passages. The chauffeur now appeared upon the path leading from the gate to the porch, but: "Stay by the car!" ordered Gatton. "Don't move without instructions."