My retirement would have looked an odd proceeding to an observer, if there had been one, for I had to retreat crabwise in order that I might keep the entrance of the alley covered with my pistol and yet see where I was going. When I reached the lamppost I scanned the area of lighted ground beneath it, and, almost at the first glance, perceived an object like a largish marble lying in the road. It proved, when I picked it up, to be a leaden ball, like an old-fashioned musket-ball, with one flattened side, which had prevented it from rolling away from the spot where it had fallen. I dropped it into my pocket and resumed my masterly retreat until, at length, the crossroads came into view. Then I quickened my pace, and as I reached the corner put away my pistol after slipping in the safety catch.
Once more out in the lighted and frequented main streets, my thoughts were free to turn over this extraordinary experience. But I did not allow them to divert me from a very careful lookout. All my scepticism was gone now. I realized that Thorndyke had not been making mere vague guesses, but that he had clearly foreseen that something of this kind would probably happen. That was, to me, the most perplexing feature of this incomprehensible affair.
I turned it over in my mind again and again, and could make nothing of it. I could see no adequate reason why this man should want to make away with me. True, I was Marion’s protector; but that—even if he were aware of it—did not seem an adequate reason. Indeed, I could not see why he was seeking to make away with her—nor, even, was it clear to me that there had been a reasonable motive for murdering her father. But as to myself, I seemed to be out of the picture altogether. The man had nothing to fear from me or to gain by my death.
That was how it appeared to me; and yet I saw plainly that I must be mistaken. There must be something behind all this—something that was unknown to me but was known to Thorndyke. What could it be? I found myself unable to make any sort of guess. In the end, I decided to call on Thorndyke the following evening, report the incident, and see if I could get any enlightenment from him.
The first part of this programme I carried out successfully enough, but the second presented more difficulties.
Thorndyke was not a very communicative man, and a perfectly impossible one to pump. What he chose to tell he told freely; and beyond that, no amount of ingenuity could extract the faintest shadow of a hint.
“I am afraid I am disturbing you, Sir,” I said in some alarm, as I noted a portentous heap of documents on the table.
“No,” he replied. “I have nearly finished, and I shall treat you as a friend, and keep you waiting while I do the little that is left.” He turned to his papers and took up his pen, but paused to cast one of his quick, penetrating glances at me.
“Has anything fresh happened?” he asked.
“Our unknown friend has had a pot at me,” I answered. “That is all.”
He laid down his pen, and leaning back in his chair, demanded particulars. I gave him an account of what had happened on the preceding night, and, taking the leaden ball from my pocket, laid it on the table. He picked it up, examined it curiously, and then placed it on the letter balance.
“Just over half an ounce,” he said. “It is a mercy it missed your head. With that weight and the velocity indicated by the flattening, it would have dropped you insensible with a fractured skull.”
“And then he would have come along and put the finishing touches, I suppose. But I wonder how he shot the thing. Could he have used an air gun?”
Thorndyke shook his head. “An air gun that would discharge a ball of that weight would make quite a loud report, and you say you heard nothing. You are quite sure of that, by the way?”
“Perfectly. The place was as silent as the grave.”
“Then he must have used a catapult; and an uncommonly efficient weapon it is in skilful hands, and as portable as a pistol. You mustn’t give him another chance, Gray.”
“I am not going to, if I can help it. But what the deuce does the fellow want to pot at me for? It is a most mysterious thing. Do you understand what it is all about, Sir?”
“I do not,” he replied. “My knowledge of the facts of this case is nearly all secondhand knowledge, derived from you. You know all that I know and probably more.”
“That is all very well, Sir,” said I; “but you foresaw that this was likely to happen. I didn’t. Therefore you must know more about the case than I do.”
He chuckled softly. “You are confusing knowledge and
