“You are quite right,” I replied. “I had in my mind to ask if it would be possible for me to retain you—I believe that is the correct expression—to investigate the case, as the police seem to think there is nothing to go on; and if the costs would be likely to be within my means.”
“As to the costs,” said he, “we can dismiss them. I see no reason to suppose that there would be any costs.”
“But your time, Sir⸺” I began.
He laughed derisively. “Do you propose to pay me for indulging in my pet hobby? No, my dear fellow, it is I who should pay you for bringing a most interesting and intriguing case to my notice. So your questions are answered. I shall be delighted to look into this case, and there will be no costs unless we have to pay for some special services. If we do, I will let you know.”
I was about to utter a protest, but he continued:
“And now, having disposed of the preliminaries, let us consider the case itself. Your very shrewd and capable inspector believes that the Scotland Yard people will take no active measures unless some new facts turn up. I have no doubt he is right, and I think they are right, too. They can’t spend a lot of time—which means public money—on a case in which hardly any data are available, and which holds out no promise of any result. But we mustn’t forget that we are in the same boat. Our chances of success are infinitesimal. This investigation is a forlorn hope. That, I may say, is what commends it to me; but I want you to understand clearly that failure is what we have to expect.”
“I understand that,” I answered gloomily, but nevertheless rather disappointed at this pessimistic view. “There seems to be nothing whatever to go upon.”
“Oh, it isn’t so bad as that,” he rejoined. “Let us just run over the data that we have. Our object is to fix the identity of the man who killed Julius D’Arblay. Let us see what we know about him. We will begin with the evidence at the inquest. From that we learned: 1. That he is a man of some education, ingenious, subtle, resourceful. This murder was planned with extraordinary ingenuity and foresight. The body was found in the pond with no telltale mark on it but an almost invisible pinprick in the back. The chances were a thousand to one, or more, against that tiny puncture ever being observed; and if it had not been observed, the verdict would have been ‘Found drowned,’ or ‘Found dead,’ and the fact of the murder would never have been discovered.
“2. We also learn that he has some knowledge of poisons. The common, vulgar, poisoner is reduced to fly-papers, weed-killer, or rat-poison—arsenic or strychnine. But this man selects the most suitable of all poisons for his purpose, and administers it in the most effective manner; with a hypodermic syringe.
“3. We learned further that he must have had some extraordinarily strong reason for making away with D’Arblay. He made most elaborate plans, he took endless trouble—for instance, it must have been no easy matter to get possession of that quantity of aconitine (unless he were a doctor, which God forbid!). That strong reason—the motive, in fact—is the key of the problem. It is the murderer’s one vulnerable point, for it can hardly be beyond discovery; and its discovery must be our principal objective.”