“Is that a flour-mill up the road there?”

“No, sir; pearl-shell.  I work there myself.”

“Pearl-shell, eh?” said Thorndyke.  “I suppose that will be an industry that will tend to attract the aliens.  Do you find it so?”

“No, sir; not at all.  The work’s too hard.  We’ve only got one foreigner in the place, and he ain’t an alien—­he’s a Jap.”

“A Jap!” exclaimed Thorndyke.  “Really.  Now, I wonder if that would chance to be our old friend Kotei—­you remember Kotei?” he added, turning to me.

“No, sir; this man’s name is Futashima.  There was another Jap in the works, a chap named Itu, a pal of Futashima’s, but he’s left.”

“Ah!  I don’t know either of them.  By the way, usen’t there to be a cab-yard just about here?”

“There’s a yard up Rankin Street where they keep vans and one or two cabs.  That chap Itu works there now.  Taken to horseflesh.  Drives a van sometimes.  Queer start for a Jap.”

“Very.”  Thorndyke thanked the man for his information, and we sauntered on towards Rankin Street.  The yard was at this time nearly deserted, being occupied only by an ancient and crazy four-wheeler and a very shabby hansom.

“Curious old houses, these that back on to the yard,” said Thorndyke, strolling into the enclosure.  “That timber gable, now,” pointing to a house, from a window of which a man was watching us suspiciously, “is quite an interesting survival.”

“What’s your business, mister?” demanded the man in a gruff tone.

“We are just having a look at these quaint old houses,” replied Thorndyke, edging towards the back of the hansom, and opening his pocket-book, as though to make a sketch.

“Well, you can see ’em from outside,” said the man.

[Illustration:  THORNDYKE’S STRATEGY.]

“So we can,” said Thorndyke suavely, “but not so well, you know.”

At this moment the pocket-book slipped from his hand and fell, scattering a number of loose papers about the ground under the hansom, and our friend at the window laughed joyously.

“No hurry,” murmured Thorndyke, as I stooped to help him to gather up the papers—­which he did in the most surprisingly slow and clumsy manner.  “It is fortunate that the ground is dry.”  He stood up with the rescued papers in his hand, and, having scribbled down a brief note, slipped the book in his pocket.

“Now you’d better mizzle,” observed the man at the window.

“Thank you,” replied Thorndyke, “I think we had;” and, with a pleasant nod at the custodian, he proceeded to adopt the hospitable suggestion.

* * * * *

“Mr. Marchmont has been here, sir, with Inspector Badger and another gentleman,” said Polton, as we entered our chambers.  “They said they would call again about five.”

“Then,” replied Thorndyke, “as it is now a quarter to five, there is just time for us to have a wash while you get the tea ready.  The particles that float in the atmosphere of Limehouse are not all mother-of-pearl.”