“Damn private about your business, aren’t you?” jeered the sentry, still in cautious tones.  “Well, you can write it down on a piece of paper and mail it to him.  He’s busy now.”

“All I want to do,” persisted Mr. William Wallace Cameron, growing slightly giddy with repressed fury, “is to ring that doorbell and ask him a question.  I’m going to do it, too.”

There was rather an interesting moment then, because the figure lunged at Mr. Cameron, and Mr. Cameron, stooping low and swiftly, as well as to one side, and at the same instant becoming a fighting Scot, which means a cool-eyed madman, got in one or two rather neat effects with his fists.  The first took the shadow just below his breast-bone, and the left caught him at that angle of the jaw where a small cause sometimes produces a large effect.  The figure sat down on the brick walk and grunted, and Mr. Cameron, judging that he had about ten seconds’ leeway, felt in the dazed person’s right hand pocket for the revolver he knew would be there, and secured it.  The sitting figure made puffing, feeble attempts to prevent him, but there was no real struggle.

Mr. Cameron himself was feeling extremely triumphant and as strong as a lion.  He was rather sorry no one had seen the affair, but that of course was sub-conscious.  And he was more cheerful than he had been for some days.  He had been up against so many purely intangible obstacles lately that it was a relief to find one he could use his fists on.

“Now I’ll have a few words with you, my desperate friend,” he said.  “I’ve got your gun, and I am hell with a revolver, because I’ve never fired one, and there’s a sort of homicidal beginner’s luck about the thing.  If you move or speak, I’ll shoot it into you first and when it’s empty I’ll choke it down your throat and strangle you to death.”

After which ferocious speech he strolled up the path, revolver in hand, and rang the doorbell.  He put the weapon in his pocket then, but he kept his hand upon it.  He had read somewhere that a revolver was quite useable from a pocket.  There was no immediate answer to the bell, and he turned and surveyed the man under the tree, faintly distinguishable in the blackness.  It had occurred to him that the number of guns a man may carry is only limited to his pockets, which are about fifteen.

There were heavy, deliberate footsteps inside, and the door was flung open.  No glare of light followed it, however.  There was a man there, alarmingly tall, who seemed to stare at him, and then beyond him into the yard.

“Well?”

“Are you Mr. Doyle?”

“I am.”

“My name is Cameron, Mr. Doyle.  I have had a small difference with your watch-dog, but he finally let me by.”

“I’m afraid I don’t understand.  I have no dog.”

“The sentry you keep posted, then.”  Mr. Cameron disliked fencing.

“Ah!” said Mr. Doyle, urbanely.  “You have happened on one of my good friends, I see.  I have many enemies, Mr. Cameron—­was that the name?  And my friends sometimes like to keep an eye on me.  It is rather touching.”