to the summerhouse, take Ralph Paton’s shoes out of the bag you brought up with you that night, slip them on, walk through the mud in them, and leave prints on the window ledge, you climb in, lock the study door on the inside, run back to the summerhouse, change back into your own shoes, and race down to the gate. (I went through similar actions the other day, when you were with Mrs. Ackroyd—it took ten minutes exactly.) Then home—and an alibi—since you had timed the dictaphone for half-past nine.”
“My dear Poirot,” I said in a voice that sounded strange and forced to my own ears, “you’ve been brooding over this case too long. What on earth had I to gain by murdering Ackroyd?”
“Safety. It was you who blackmailed Mrs. Ferrars. Who could have had a better knowledge of what killed Mr. Ferrars than the doctor who was attending him? When you spoke to me that first day in the garden, you mentioned a legacy received about a year ago. I have been unable to discover any trace of a legacy. You had to invent some way of accounting for Mrs. Ferrars’s twenty thousand pounds. It has not done you much good. You lost most of it in speculation—then you put the screw on too hard, and Mrs. Ferrars took a way out that you had not expected. If Ackroyd had learnt the truth he would have had no mercy on you—you were ruined forever.”
“And the telephone call?” I asked, trying to rally. “You have a plausible explanation of that also, I suppose?”
“I will confess to you that it was my greatest stumbling block when I found that a call had actually been put through to you from King’s Abbot station. I at first believed that you had simply invented the story. It was a very clever touch, that. You must have some excuse for arriving at Fernly, finding the body, and so getting the chance to remove the dictaphone on which your alibi depended. I had a very vague notion of