All that had remained mysterious in the earlier cases now became clear. In the first, the case of Samuel's diamonds, Denson had been put into the office where Samuel had found him, by Mayes, with the express design of effecting a diamond robbery. The robbery was effected, and the unhappy Denson formed a plan of making a bolt of it himself with the diamonds. He was, perhaps, what is called a difficult subject in hypnotism--amenable enough to direct influence, but not sufficiently retentive of post-hypnotic suggestion. He hid the jewels and adopted a disguise, but Mayes was watching him better than he supposed. The diamonds were lost, but Denson was found and done to death--probably not in that retreat near Barbican, but at night in some empty street. The diamonds were not found on him, and the body, with the mark of the Triangle still on it, was taken by night to a central spot in London and there left. Mayes probably thought that a notable example like this, so boldly displayed and so conspicuously reported in the Press, would impress his auxiliaries throughout London with the terror that was one of his weapons; for they would well understand the meaning of the Red Triangle, and they would receive a striking illustration of the consequences of rebellion or bad faith. The money and the watch were left in the pockets because they were trifles after the loss of fifteen thousand pounds' worth of diamonds, and their presence in the pockets made the murder the less easy to understand--which was a point gained. And as to the keys--Mayes knew nothing of where the diamonds were hidden, and so had no use for them. For where could he use them? Denson had left his lodgings, and as to the office, that, he would guess, would be in the hands of the police, on Samuel's complaint. The immediate result of this affair on the only honest member of Mayes's circle I have told in the case of Mr. Jacob Mason. He was not yet thoroughly in Mayes's hands, but he had "dabbled," as he remorsefully confessed, and Mayes had already found him useful. He was dangerous, and his end came quickly. Another victim who had probably begun innocently enough was Henning, the clerk to Kingsley, Bell and Dalton, and his death in the Penn's Meadow barn leaves a mystery that never can be positively cleared up. Was it murder or was it suicide by post-hypnotic suggestion? It will be remembered that the fire burst out in the barn after Mayes had left it.