“I think you have,” he said quietly.

 

“But——”

 

“Have you told me everything known to you about this young man Paton?” He smiled

as I grew red. “Oh! do not fear. I will not press you. I shall learn it in good

time.”

 

“I wish you’d tell me something of your methods,” I said hastily, to cover my

confusion. “The point about the fire, for instance?”

 

“Oh! that was very simple. You leave Mr. Ackroyd at—ten minutes to nine, was it

not?”

 

“Yes, exactly, I should say.”

 

“The window is then closed and bolted and the door unlocked. At a quarter past

ten when the body is discovered, the door is locked and the window is open. Who

opened it? Clearly only Mr. Ackroyd himself could have done so, and for one of

two reasons. Either because the room became unbearably hot (but since the fire

was nearly out and there was a sharp drop in temperature last night, that cannot

be the reason), or because he admitted some one that way. And if he admitted

some one that way, it must have been some one well known to him, since he had

previously shown himself uneasy on the subject of that same window.”