As a mere matter of form he waited for the report of the constable who had gone in quest of Sowerby, but it merely confirmed the fact that Sowerby had left Scotland Yard over three hours earlier. Dunbar summoned a taxicab and proceeded to the house of Dr. Stuart. CHAPTER VII CONTENTS OF THE SEALED ENVELOPE Stuart personally admitted Dunbar, and once more the Inspector found himself in the armchair in the study. The fire was almost out and the room seemed to be chilly. Stuart was labouring under the influence of suppressed excitement and was pacing restlessly up and down the floor. "Inspector," he began, "I find it difficult to tell you the facts which have recently come to my knowledge bearing upon this most mysterious 'Scorpion' case. I clearly perceive, now, that without being aware of the fact I have nevertheless been concerned in the case for at least a week." Dunbar stared surprisedly, but offered no comment. "A fortnight ago," Stuart continued, "I found myself in the neighbourhood of the West India Docks. I had been spending the evening with a very old friend, chief officer of a liner in dock. I had intended to leave the ship at about ten o'clock and to walk to the railway station, but, as it fell out, the party did not break up until after midnight. Declining the offer of a berth on board, I came ashore determined to make my way home by tram and afoot. I should probably have done so and have been spared--much; but rain began to fall suddenly and I found myself, foolishly unprovided with a top-coat, in those grey East End streets without hope of getting a lift. "It was just as I was crossing Limehouse Causeway that I observed, to my astonishment, the head-lamps of a cab or car shining out from a dark and forbidding thoroughfare which led down to the river. The sight was so utterly unexpected that I paused, looking through the rainy mist in the direction of the stationary vehicle. I was still unable to make out if it were a cab or a car, and accordingly I walked along to where it stood and found that it was a taxicab and apparently for hire. "'Are you disengaged?' I said to the man. "'Well, sir, I suppose I am,' was his curious reply. 'Where do you want to go?' "I gave him this address and he drove me home. On arriving, so grateful did I feel that I took pity upon the man, for it had settled down into a brute of a night, and asked him to come in and take a glass of grog. He was only too glad to do so. He turned out to be quite an intelligent sort of fellow, and we chatted together for ten minutes or so. "I had forgotten all about him when, I believe on the following night, he reappeared in the character of a patient. He had a badly damaged skull, and I gathered that he had had an accident with his cab and had been pitched out into the road.