Still wondering at my heartlessness, I turned and walked in the direction of Yarby. But I had more important matters than my own mental attitude to consider, for the first thing which I had to ask myself was, “By whose hand did Green meet his end?” It was, of course, possible either that he had committed suicide, or that the paper bearing the signature of “Captain Shannon” had been placed where I found it by some one who, for reasons of his own, had taken Green’s life, and hoped by attributing the crime to Captain Shannon to divert suspicion from himself. But I soon decided that neither of these alternatives was worth consideration. For the motive of the crime one had not far to look. Green had, on his own showing, discovered something which might lead to Captain Shannon’s arrest, and there could be no doubt that, should the fugitive get wind of this, his first step would be to rid himself of so dangerous an enemy. From the circumstance under which I discovered the body of my unfortunate agent, I came to the conclusion that he was on board a yacht when the crime was effected. Having often yachted off Yarby I was tolerably familiar with the coast, and knew that the place where I found the body was the very spot towards which, with every incoming tide, a strong current sets. And as matters stood it looked as if the corpse had been carried thither from the open sea. That it had not been placed where it was by any one on the shore--at all events since the outgoing tide--was evident from the fact that my own were the only footmarks on the soft smooth stretch of sandy mud which led down to the water’s edge. But what struck me as especially strange was that, though Green was otherwise fully dressed, he was wearing no boots. It was very unlikely that he had walked two miles along a rocky beach with unprotected feet. But if he had, for any reason, been persuaded to go upon a yacht, it was quite possible that he might take his boots off--firstly, because no yacht owner who prides himself upon the trimness of his craft and the whiteness of her decks cares to have a visitor tramping about in heavy and perhaps muddy boots; and secondly, because a landsman who is so shod would find it difficult to get a safe foothold upon the slippery decks of a small vessel. My theory was that Green had been decoyed upon a yacht under some pretext, or that he had been foolhardy enough to go on board of his own accord, perhaps in the hope of obtaining further and final evidence of Mullen’s identity, or, it may be, with the idea of achieving the fugitive’s arrest. Once on board, he had in all probability been the victim of foul play. Very likely he had been rendered insensible by a blow on the head given from behind, after which he had been carried out to sea, where he could be despatched at leisure, and without any risk of his cries being heard or the act witnessed, as might be the case on land. After that the bottle