Towards eleven o'clock at night the fog began slightly to lift. As Kerry crossed the bridge over Limehouse Canal he could vaguely discern the dirty water below, and street lamps showed dimly, surrounded each by a halo of yellow mist. Fog signals were booming on the railway, and from the great docks in the neighborhood mechanical clashings and hammerings were audible.  
Turning to the right, Kerry walked on for some distance, and then suddenly stepped into the entrance to a narrow cul-de-sac and stood quite still.
 
A conviction had been growing upon him during the past twelve hours that someone was persistently and cleverly dogging his footsteps. He had first detected the presence of this mysterious follower outside the house of Sin Sin Wa, but the density of the fog had made it impossible for him to obtain a glimpse of the man's face. He was convinced, too, that he had been followed back to Leman Street, and from there to New Scotland Yard. Now, again he became aware of this persistent presence, and hoped at last to confront the spy.
 
Below footsteps, the footsteps of someone proceeding with the utmost caution, came along the pavement. Kerry stood close to the wall of the court, one hand in a pocket of his overall, waiting and chewing.
 
Nearer came the footsteps—and nearer. A shadowy figure appeared only a yard or so away from the watchful Chief Inspector. Thereupon he acted.
 
With one surprising spring he hurled himself upon the unprepared man, grasped him by his coat collar, and shone the light of an electric torch fully into his face.
 
“Hell!” he snapped. “The smart from Spinker's!”
 
The ray of the torch lighted up the mean, pinched face of Brisley, blanched now by fright, gleamed upon the sharp, hooked nose and into the cunning little brown eyes. Brisley licked his lips. In Kerry's muscular grip he bore quite a remarkable resemblance to a rat in the jaws of a terrier.
 
“Ho, ho!” continued the Chief Inspector, showing his teeth savagely. “So we let Scotland Yard make the pie, and then we steal all the plums, do we?”
 
He shook the frightened man until Brisley's broad-brimmed bowler was shaken off, revealing the receding brow and scanty neutral-colored hair.
 
“We let Scotland Yard work night and day, and then we present our rat-faced selves to Mr. Monte Irvin and say we have 'found the lady' do we?” Another vigorous shake followed. “We track Chief Inspectors of the Criminal Investigation Department, do we? We do, eh? We are dirty, skulking mongrels, aren't we? We require to be kicked from Limehouse to Paradise, don't we?” He suddenly released Brisley. “So we shall be!” he shouted furiously.
 
Hot upon the promise came the deed.
 
Brisley sent up a howl of pain as Kerry's right brogue came into violent contact with his person. The assault almost lifted him off his feet, and hatless as he was he set off, running as a man runs whose life depends upon his speed. The sound of his pattering footsteps was echoed from wall to wall of the cul-de-sac until finally it was swallowed up in the fog.
 
Kerry stood listening for some moments, then, directing a furious kick upon the bowler which lay at his feet, he snapped off the light of the torch and pursued his way. The lesser mystery was solved, but the greater was before him.
 
He had made a careful study of the geography of the neighborhood, and although the fog was still dense enough to be confusing, he found his way without much difficulty to the street for which he was bound. Some fifteen paces along the narrow thoroughfare he came upon someone standing by a closed door set in a high brick wall. The street contained no dwelling houses, and except for the solitary figure by the door was deserted and silent. Kerry took out his torch and shone a white ring upon the smiling countenance of Detective-Sergeant Coombes.
 
“If that smile gets any worse,” he said irritably, “they'll have to move your ears back. Anything to report?”
 
“Sin Sin Wa went to bed an hour ago.”
 
“Any visitors?”
 
“No.”
 
“Has he been out?”
 
“No.”
 
“Got the ladder?”
 
“Yes.”
 
“All quiet in the neighborhood?”
 
“All quiet.”
 
“Good.”
 
The street in which this conversation took place was one running roughly parallel with that in which the house of Sin Sin Wa was situated. A detailed search of the Chinaman's premises had failed to bring to light any scrap of evidence to show that opium had ever been smoked there. Of the door described by Mollie Gretna, and said to communicate with the adjoining establishment, not a trace could be found. But the fact that such a door had existed did not rest solely upon Mollie's testimony. From one of the “beat-ups” interviewed that day, Kerry had succeeded in extracting confirmatory evidence.
 
Inquiries conducted in the neighborhood of Poplar had brought to light the fact that four of the houses in this particular street, including that occupied by Sin Sin Wa and that adjoining it, belonged to a certain Mr. Jacobs, said to reside abroad. Mr. Jacob's rents were collected by an estate agent, and sent to an address in San Francisco. For some reason not evident to this man of business, Mr. Jacobs demanded a rental for the house next to Sin Sin Wa's, which was out of all proportion to the value of the property. Hence it had remained vacant for a number of years. The windows were broken and boarded up, as was the door.
 
Kerry realized that the circumstance of the landlord of “The House of a Hundred Raptures” being named Jacobs, and the lessee of the Cubanis Cigarette Company's premises in old Bond Street being named Isaacs, might be no more than a coincidence. Nevertheless it was odd. He had determined to explore the place without unduly advertising his intentions.
 
Two modes of entrance presented themselves. There was a trap on the roof, but in order to reach it access would have to be obtained to one of the other houses in the row, which also possessed a roof-trap; or there were four windows overlooking a little back yard, two upstairs and two down.
 
By means of a short ladder which Coombes had brought for the purpose Kerry climbed on to the wall and dropped into the yard.
 
“The jemmy!” he said softly.
 
Coombes, also mounting, dropped the required implement. Kerry caught it deftly, and in a very few minutes had wrenched away the rough planking nailed over one of the lower windows, without making very much noise.
 
“Shall I come down?” inquired Coombes in muffled tones from the top of the wall.
 
“No,” rapped Kerry. “Hide the ladder again. If I want help I'll whistle. Catch!”
 
He tossed the jemmy up to Coombes, and Coombes............