“I fear, Watson,” said he, “that you will not improve any reputation which I may have acquired by adding the case of the Thor Bridge mystery to your annals. I have been sluggish in mind and wanting in that mixture of imagination and reality which is the basis of my art. I confess that the chip in the stonework was a sufficient clue to suggest the true solution, and that I blame myself for not having attained it sooner.

“It must be admitted that the workings of this unhappy woman’s mind were deep and subtle, so that it was no very simple matter to unravel her plot. I do not think that in our adventures we have ever come across a stranger example of what perverted love can bring about. Whether Miss Dunbar was her rival in a physical or in a merely mental sense seems to have been equally unforgivable in her eyes. No doubt she blamed this innocent lady for all those harsh dealings and unkind words with which her husband tried to repel her too demonstrative affection. Her first resolution was to end her own life. Her second was to do it in such a way as to involve her victim in a fate which was worse far than any sudden death could be.