The man stroked his shaven jaws in the deliberate manner of a person about to precipitate a crisis.  Pendleton leaned toward him, anxiously.

“What sort of sounds?” he asked.

“There were two,” replied the cab driver.  “The first was a revolver shot; the second came right after, and was a kind of a scream—­like that of a parrot.”

“And what then?” asked Ashton-Kirk, easily.

“There wasn’t anything for a few minutes, anyway.  But the revolver shot had kind of got my attention, so I was taking notice of the windows.  Then suddenly I caught sight of the woman.  You see, the gas-light was near the window and she kind of leaned over and turned it out.  It was only for a time as long as that,” and the man snapped his fingers.  “But I saw her plain.  Then I heard her coming down the stairs to the street—­almost at a run.  She banged the street door shut after her, jumped into her car and went tearing away as if she was crazy.  I stayed fifteen minutes before I got a fare; but nothing else happened.”

Pendleton’s hand closed hard on the edge of the chair he sat in.  There was a moment’s silence; then Ashton-Kirk asked: 

“Just where was your cab standing at this time?”

“Right in front of McCausland’s door.”

“And you were on the box?”

“Yes.”

The investigator put a piece of money in the man’s hand as he and Pendleton arose and prepared to go.

“Say,” said Sam curiously, “I’ve been in bed all day and ain’t heard a word of anything.  Who’s been done up?”

“Hume.  Stabbed in the chest.”

“Shot, you mean.”

“No, I mean stabbed.  With a bayonet.”

The man stared wonderingly.

“G’way,” he said.

They bid him good-day and tramped down the three long flights to the street.  Pendleton was silent, and walked with his head held down.

“We have more than an hour of good daylight left,” said his friend, as they reached the street.  “And as I must have a good unrestricted look at Hume’s apartments before everything is hopelessly changed about, suppose we go there now.  We can get a taxi in the next street.”

“Just a moment,” said Pendleton.  “Before we take another step in the matter, Kirk, I must ask a question.”

Ashton-Kirk put his hand upon his friend’s shoulder.

“Don’t,” said he.  “I know just what the question would be, and at the present time I can’t answer it.  At this moment, except for some few theories that I have yet to verify, I am as much puzzled as yourself.”

“But,” and there was a tremble in the speaker’s voice, “you must answer me, old chap—­and you must answer now.”

The catch in his voice, the expression upon the young man’s face caused Ashton-Kirk to grasp an astonishing fact.  The hand that he had laid upon Pendleton’s shoulder tightened as he answered: 

“Yes, Edyth Vale is concerned.  As a rule I do not speak of my clients to others, but in view of what you have already heard and seen, it would be a waste of words to deny it.  But, see here, there are lots of things we don’t know yet about this business.  It may look very different in a few hours.  Come.”