“Quite,” I replied, “and it also follows that if the bar gave way anyone thus leaning on it would be pitched into the street.”

“Your reasoning is correct.”

“But, my dear fellow,” said I, “how could such an accident have been foreseen?”

“You speak of an accident.  This was no accident!  One end of the bar had been filed completely through, although the file marks had been carefully concealed with rust and dirt; and the other end had been wrenched out from its socket and then replaced in such a way that anyone leaning upon the bar could not fail to be precipitated into the street!”

“Good heavens!   Then you mean------”

“I mean, Knox, that the man who occupied the supper room on the night before the tragedy—­the dark man, tanned and bearded, with slightly oblique eyes—–­spent his time in filing through that bar—­in short, in preparing a death trap!”

I was almost dumbfounded.

“But, Harley,” I said, “assuming that he knew his victim would be
the next occupant of the room, how could he know------?”

I stopped.  Suddenly, as if a curtain had been raised, the details of what I now perceived to be a fiendishly cunning murder were revealed to me.

“According to his own account, Knox,” resumed Harley, “Major Ragstaff regularly passed along that street with military punctuality at the same hour every night.  You may take it for granted that the murderer was well aware of this.  As a matter of fact, I happen to know that he was.  We must also take it for granted that the murderer knew of these little dinners for two which took place in the private room above the Cafe Dame every Wednesday—­and sometimes on Friday.  Around the figure of the methodical major—­with his conspicuous white hat as a sort of focus—­was built up one of the most ingenious schemes of murder with which I have ever come in contact.  The victim literally killed himself.”

“But, Harley, the victim might have ignored the disturbance.”

“That is where I first detected the touch of genius, Knox.  He recognized the voice of one of the combatants—­or his companion did.  Here we are.”

The cab drew up before the house in Hamilton Place.  We alighted, and Harley pressed the bell.  The same footman whom I had seen admit the woman opened the door.

“Is Lady Ireton at home?” asked Harley.

As he uttered the name I literally held my breath.  We had come to the house of Major Ragstaff’s daughter, the Marchioness of Ireton, one of society’s most celebrated and beautiful hostesses!—­the wife of a peer famed alike as sportsman, soldier, and scholar.

“I believe she is dining at home, sir,” said the man.  “Shall I inquire?”

“Be good enough to do so,” replied Harley, and gave him a card.  “Inform her that I wish to return to her a handbag which she lost a few days ago.”

The man ushered us into an anteroom opening off the lofty and rather gloomy hall, and as the door closed: