“Very well, then, I will endeavour to be brief. Do you recollect Miss Beverley’s story of the unfamiliar footsteps which passed her door on several occasions?”

“Perfectly.”

“You recollect that you, yourself, heard someone crossing the hall, and that both of us heard a door close?”

“We did.”

“And finally you saw the shadow of a woman upon the blind of the Colonel’s private study. Very well. Excluding the preposterous theory of Inspector Aylesbury, there is no woman in Cray’s Folly whose footsteps could possibly have been heard in that corridor, and whose shadow could possibly have been seen upon the blind of Colonel Menendez’s room.”

“I agree,” said Harley, quietly. “I have definitely eliminated all the servants from the case. Therefore, proceed, Knox, I am all attention.”

“I will do so. There is a door on the south side of the house, close to the tower and opening into the rhododendron shrubbery. This was the door used by Colonel Menendez in his somnambulistic rambles, according to his own account. Now, assuming his statement to have been untrue in one particular, that is, assuming he was not walking in his sleep, but was fully awake—”

“Eh?” exclaimed Harley, his expression undergoing a subtle change. “Do you think his statement was untrue?”

“According to my theory, Harley, his statement was untrue, in this particular, at least. But to proceed: Might he not have employed this door to admit a nocturnal visitor?”

“It is feasible,” muttered Harley, watching me closely.