“Yes, my good Parker. I have in mind a little experiment. I have placed Major Blunt on the terrace outside the study window. I want to see if anyone there could have heard the voices of Miss Ackroyd and yourself in the lobby that night. I want to enact that little scene over again. Perhaps you would fetch the tray or whatever it was you were carrying?”

Parker vanished, and we repaired to the lobby outside the study door. Presently we heard a chink in the outer hall, and Parker appeared in the doorway carrying a tray with a siphon, a decanter of whisky, and two glasses on it.

“One moment,” cried Poirot, raising his hand and seemingly very excited. “We must have everything in order. Just as it occurred. It is a little method of mine.”

“A foreign custom, sir,” said Parker. “Reconstruction of the crime they call it, do they not?”

He was quite imperturbable as he stood there politely waiting on Poirot’s orders.