"We come to another person who profited by Farrell's death, Dr. Morrison," said Quarles. "He married Miss Lester not long afterwards. It is known that he was friendly, or apparently friendly, with his rival, for such Farrell was, although he may not have been aware of the fact; and, curiously enough, Morrison called at the office in Austin Friars on the fatal day, and wanted to see Farrell an hour or so after he had left." "Yes; I thought it was curious at the time." "He was able to account for his subsequent doings that day," Quarles went on; "so it seems impossible that he could have been the person Farrell brought back to the office that night. I think we must say positively he was not. At the same time we must not overlook the fact that in his case there was a motive for the crime. Forgetting for a moment our conclusion that some one must have been in the office with Farrell in order to make the death appear like suicide, we ask whether in any way it was possible for Morrison to administer poison to Farrell. Supposing Farrell had met Morrison immediately upon leaving the office, could the doctor possibly have given him poison in such a manner that it would not take effect for hours after?" "Stood him a glass of wine somewhere, you mean?" "Or induced him to swallow a tablet," said Quarles. "It is really a new idea," said our host. "It is a possibility, of course," Quarles answered; "but not a very likely one, I fancy. It might account for the tumbler. Farrell might have felt ill and drunk some plain water, but why was he in the office at all? I find the whole crux of the affair in that question. Why should he come back when he had left for the day?" "Then you are inclined to exonerate Morrison?" "On the evidence, yes." "You speak with some reservation, Mr. Quarles." "I want to bring the whole argument into focus, as it were," the professor went on. "It was a settlement day on the Stock Exchange. I believe a point was made three years ago that it was curious no one had seen Farrell return, since many people who knew him would be about Austin Friars late that night. This does not seem to me much of an argument. If he returned between nine and ten he might easily escape notice. What does seem to me curious is that he should choose such a day to leave the office early, and tell a lie about it into the bargain. He said he had an appointment with Miss Lester, and we know he had not." "Ought we not to say that we know she says he had not?" Delverton corrected. "I do not wish to be captious, but--" "You are quite right," said Quarles; "we must be precise. You knew Miss Lester, of course?" "I did not see her until after Farrell's death, then I saw her several times. She seemed rather a charming person." "You have not seen her since her marriage?" "No."