“You mean—­tell him I am no longer certain as to the hour of that struggle?”

“Precisely.  I give you my word that young Fraser-Freer will not be permanently incriminated by such an act on your part.  And incidentally you will be aiding me.”

“Very well,” said I.  “But I don’t understand this at all.”

“No—­of course not.  I wish I could explain to you; but I can not.  I will say this—­the death of Captain Fraser-Freer is regarded as a most significant thing by the War Office.  Thus it happens that two distinct hunts for his assassin are under way—­one conducted by Bray, the other by me.  Bray does not suspect that I am working on the case and I want to keep him in the dark as long as possible.  You may choose which of these investigations you wish to be identified with.”

“I think,” said I, “that I prefer you to Bray.”

“Good boy!” he answered.  “You have not gone wrong.  And you can do me a service this evening, which is why I was on the point of coming here, even before you telephoned me.  I take it that you remember and could identify the chap who called himself Archibald Enwright —­the man who gave you that letter to the captain?”

“I surely could,” said I.

“Then, if you can spare me an hour, get your hat.”

And so it happens, lady of the Carlton, that I have just been to Limehouse.  You do not know where Limehouse is and I trust you never will.  It is picturesque; it is revolting; it is colorful and wicked.  The weird odors of it still fill my nostrils; the sinister portrait of it is still before my eyes.  It is the Chinatown of London —­Limehouse.  Down in the dregs of the town—­with West India Dock Road for its spinal column—­it lies, redolent of ways that are dark and tricks that are vain.  Not only the heathen Chinee so peculiar shuffles through its dim-lit alleys, but the scum of the earth, of many colors and of many climes.  The Arab and the Hindu, the Malayan and the Jap, black men from the Congo and fair men from Scandinavia —­these you may meet there—­the outpourings of all the ships that sail the Seven Seas.  There many drunken beasts, with their pay in their pockets, seek each his favorite sin; and for those who love most the opium, there is, at all too regular intervals, the Sign of the Open Lamp.

We went there, Colonel Hughes and I. Up and down the narrow Causeway, yellow at intervals with the light from gloomy shops, dark mostly because of tightly closed shutters through which only thin jets found their way, we walked until we came and stood at last in shadow outside the black doorway of Harry San Li’s so-called restaurant.  We waited ten, fifteen minutes; then a man came down the Causeway and paused before that door.  There was something familiar in his jaunty walk.  Then the faint glow of the lamp that was the indication of Harry San’s real business lit his pale face, and I knew that I had seen him last in the cool evening at Interlaken, where Limehouse could not have lived a moment, with the Jungfrau frowning down upon it.