"Sir," said he, "it is unnecessary for me to state that your surmise in regard to my past convictions is true. If Miss Dare was not with my aunt just before the murder, I certainly had reasons for thinking she was. To be sure, I did not see her or hear her voice, but I heard my aunt address her distinctly and by name." "You did?" Mr. Gryce's interest in the tattoo he was playing on his knee became intense. "Yes. It was just as I pushed the door ajar. The words were these: 'You think you are going to marry him, Imogene Dare; but I tell you you _never shall_, not while _I_ live.'" "Humph!" broke involuntarily from the detective's lips, and, though his face betrayed nothing of the shock this communication occasioned him, his fingers stopped an instant in their restless play. Mr. Mansell saw it and cast him an anxious look. The detective instantly smiled with great unconcern. "Go on," said he, "what else did you hear?" "Nothing else. In the mood in which I was this very plain intimation that Miss Dare had sought my aunt, had pleaded with her for me and failed, struck me as sufficient. I did not wait to hear more, but hurried away in a state of passion that was little short of frenzy. To leave the place and return to my work was now my one wish. When I found, then, that by running I might catch the train at Monteith, I ran, and so unconsciously laid myself open to suspicion." "I see," murmured the detective; "I see." "Not that I suspected any evil then," pursued Mr. Mansell, earnestly. "I was only conscious of disappointment and a desire to escape from my own thoughts. It was not till next day----" "Yes--yes," interrupted Mr. Gryce, abstractedly, "but your aunt's words! She said: 'You think you are going to marry him, Imogene Dare; but you never shall, not while I live.' Yet Imogene Dare was not there. Let us solve that problem." "You think you can?" "I think I must." "How? how?" The detective did not answer. He was buried in profound thought. Suddenly he exclaimed: "It is, as you say, the key-note to the tragedy. It must be solved." But the glance he dived deep into space seemed to echo that "How? how?" of the prisoner, with a gloomy persistence that promised little for an immediate answer to the enigma before them. It occurred to Mansell to offer a suggestion. "There is but one way _I_ can explain it," said he. "My aunt was speaking to herself. She was deaf and lived alone. Such people often indulge in soliloquizing." The slap which Mr. Gryce gave his thigh must have made it tingle for a good half-hour. "There," he cried, "who says extraordinary measures are not useful at times? You've hit the very explanation. Of course she was speaking to herself. She was just the woman to do it. Imogene Dare was in her thoughts, so she addressed Imogene Dare. If you had opened the door you would have seen her standing there alone, venting her thoughts into empty space." "I wish I had," said the prisoner.