At about the time that this conversation was taking place in Ho-Pin's catacombs, Detective-Inspector Dunbar and Detective-Sergeant Sowerby were joined by a third representative of New Scotland Yard at the appointed spot by the dock gates. This was Stringer, the detective to whom was assigned the tracing of the missing Soames; and he loomed up through the rain-mist, a glistening but dejected figure.  
“Any luck?” inquired Sowerby, sepulchrally.
 
Stringer, a dark and morose looking man, shook his head.
 
“I've beaten up every 'Chink' in Wapping and Limehouse, I should reckon,” he said, plaintively. “They're all as innocent as babes unborn. You can take it from me: Chinatown hasn't got a murder on its conscience at present. BRR! it's a beastly night. Suppose we have one?”
 
Dunbar nodded, and the three wet investigators walked back for some little distance in silence, presently emerging via a narrow, dark, uninviting alleyway into West India Dock Road. A brilliantly lighted hostelry proved to be their objective, and there, in a quiet corner of the deserted billiard room, over their glasses, they discussed this mysterious case, which at first had looked so simple of solution if only because it offered so many unusual features, but which, the deeper they probed, merely revealed fresh complications.
 
“The business of those Fry people, in Scotland, was a rotten disappointment,” said Dunbar, suddenly. “They were merely paid by the late Mrs. Vernon to re-address letters to a little newspaper shop in Knightsbridge, where an untraceable boy used to call for them! Martin has just reported this evening. Perth wires for instructions, but it's a dead-end, I'm afraid.”
 
“You know,” said Sowerby, fishing a piece of cork from the brown froth of a fine example by Guinness, “to my mind our hope's in Soames; and if we want to find Soames, to my mind we want to look, not east, but west.”
 
“Hear, hear!” concorded Stringer, gloomily sipping hot rum.
 
“It seems to me,” continued Sowerby, “that Limehouse is about the last place in the world a man like Soames would think of hiding in.”
 
“It isn't where he'll be THINKING of hiding,” snapped Dunbar, turning his fierce eyes upon the last speaker. “You can't seem to get the idea out of your head, Sowerby, that Soames is an independent agent. He ISN'T an independent agent. He's only the servant; and through the servant we hope to find the master.”
 
“But why in the east-end?” came the plaintive voice of Stringer; “for only one reason, that I can see—because Max says that there's a Chinaman in the case.”
 
“There's opium in the case, isn't there?” said Dunbar, adding more water to his whisky, “and where there's opium there is pretty frequently a Chinaman.”
 
“But to my mind,” persisted Sowerby, his eyebrows drawn together in a frown of concentration, “the place where Mrs. Vernon used to get the opium was the place we raided in Gillingham Street.”
 
“Nurse Proctor's!” cried Stringer, banging his fist on the table. “Exactly my idea! There may have been a Chinaman concerned in the management of the Gillingham Street stunt, or there may not, but I'll swear that was where the opium was supplied. In fact I don't think that there's any doubt about it. Medical evidence (opinions differed a bit, certainly) went to show that she had been addicted to opium for some years. Other evidence—you got it yourself, Inspector—went to show that she came from Gillingham Street on the night of the murder. Gillingham Street crowd vanished like a beautiful dream before we had time to nab them! What more do you want? What are we up to, messing about in Limehouse and Wapping?”
 
Sowerby partook of a long drink and turned his eyes upon Dunbar, awaiting the inspector's reply.
 
“You both have the wrong idea!” said Dunbar, deliberately; “you are all wrong! You seem to be under the impression that if we could lay our hands upon the missing staff of the so-called Nursing Home, we should find the assassin to be one of the crowd. It doesn't follow at all. For a long time, you, Sowerby,”—he turned his tawny eyes upon the sergeant—“had the idea that Soames was the murderer, and I'm not sure that you have got rid of it yet! You, Stringer, appear to think that Nurse Proctor is responsible. Upon my word, you are a hopeless pair! Suppose Soames had nothing whatever to do with the matter, but merely realized that he could not prove an alibi? Wouldn't YOU bolt? I put it to you.”
 
Sowerby stared hard, and Stringer scratched his chin, reflectively.
 
“The same reasoning applies to the Gillingham Street people,” continued Dunbar. “We haven't the slightest idea of THEIR whereabouts because we don't even know who they were; but we do know something about Soames, and we're looking for him, not because we think he did the murder, but because we think he can tell us who did.”
 
“Which brings us back to the old point,” interrupted Stringer, softly beating his fist upon the table at every word; “why are we looking for Soames in the east-end?”
 
“Because,” replied Dunbar, “we're working on the theory tha............