“You really believe that one of those people here to-night committed the murder?” I asked incredulously.
“Yes, my friend.”
“Which one?”
There was a silence for some minutes. Then Poirot tossed the stump of his cigarette into the grate and began to speak in a quiet, reflective tone.
“I will take you the way that I have traveled myself. Step by step you shall accompany me, and see for yourself that all the facts point indisputably to one person. Now, to begin with, there were two facts and one little discrepancy in time which especially attracted my attention. The first fact was the telephone call. If Ralph Paton were indeed the murderer, the telephone call became meaningless and absurd. Therefore, I said to myself, Ralph Paton is not the murderer.
“I satisfied myself that the call could not have been sent by any one in the house, yet I was convinced that it was amongst those present on the fatal evening that I had to look for my criminal. Therefore I concluded that the telephone call must have been sent by an accomplice. I was not quite pleased with that deduction, but I let it stand for the minute.
“I next examined the motive for the call. That was difficult. I could only get at it by judging its result. Which was—that the murder was discovered that night instead of—in all probability—the following morning. You agree with that?”
“Ye-es,” I admitted. “Yes. As you say, Mr. Ackroyd, having given orders that he was not to be disturbed, nobody would have been likely to go to the study that night.”
“Très bien. The affair marches, does it not? But matters were still obscure. What was the advantage of having the crime discovered that night in preference to the following morning? The only idea I could get hold of was that the murderer, knowing the crime was to be discovered at a certain time, could make sure of being present when the door was broken in—or at any rate immediately afterwards. And now we come to the second fact—the chair pulled out from the wall. Inspector Raglan dismissed that as of no importance. I, on the contrary, have always regarded it as of supreme importance.
“In your manuscript you have drawn a neat little plan of the study. If you had it with you this minute you would see that—the chair being drawn out in the position indicated by Parker—it would stand in a direct line between the door and the window.”