“Well, it figures out that way, does it not? Here he is, sending out messages to an accomplice—there are several of his gang in London. Then suddenly, just as by your own account he was telling them that there was danger, he broke short off. What could it mean except that from the window he had suddenly either caught sight of us in the street, or in some way come to understand how close the danger was, and that he must act right away if he was to avoid it? What do you suggest, Mr. Holmes?”

“That we go up at once and see for ourselves.”

“But we have no warrant for his arrest.”

“He is in unoccupied premises under suspicious circumstances,” said Gregson. “That is good enough for the moment. When we have him by the heels we can see if New York can't help us to keep him. I'll take the responsibility of arresting him now.”

Our official detectives may blunder in the matter of intelligence, but never in that of courage. Gregson climbed the stair to arrest this desperate murderer with the same absolutely quiet and businesslike bearing with which he would have ascended the official staircase of Scotland Yard. The Pinkerton man had tried to push past him, but Gregson had firmly elbowed him back. London dangers were the privilege of the London force.

The door of the left-hand flat upon the third landing was standing ajar. Gregson pushed it open. Within all was absolute silence and darkness. I struck a match and lit the detective's lantern. As I did so, and as the flicker steadied into a flame, we all gave a gasp of surprise. On the deal boards of the carpetless floor there was outlined a fresh track of blood. The red steps pointed towards us and led away from an inner room, the door of which was closed. Gregson flung it open and held his light full blaze in front of him, while we all peered eagerly over his shoulders.