He found himself doubting the success of those tactics upon which, earlier in the day, he had congratulated himself.  Perhaps beneath the guise of Hampden, who bought antique furniture on commission, those cunning old eyes beneath the horn-rimmed spectacles had perceived the detective hidden, or at least had marked subterfuge.

While he could not count Lala a conquest—­for he had not even attempted to make love to her—­the ease with which he had developed the acquaintance now, afforded matter for suspicion.

At the entrance to the court communicating with the establishment of Huang Chow he paused, looking cautiously about him.  The men on the Limehouse beats had been warned of the investigation afoot tonight, and there was a plain-clothes man on point duty at no great distance away, although carefully hidden, so that Durham had quite failed to detect his presence.

Durham wore rough clothes and rubber-soled shoes; and now, as he entered the court, he was thinking of the official report of the police sergeant who, not so many hours before, had paid a visit to the house of Huang Chow in order to question him respecting his knowledge of the dead man Cohen, and to learn when last he had seen him.

Old Huang, who had received his caller in the large room upstairs, the room which boasted the presence of the writing-dais, had exhibited no trace of confusion, assuring the sergeant that he had not seen the man Cohen for several days.  Cohen had come to him with an American introduction, which he, Huang, believed to be forged, and had wanted him to undertake a shady agency, respecting the details of which he remained peculiarly reticent.  In short, nothing had been gained by this official interrogation, and Huang blandly denied any knowledge of an attempted burglary of his establishment.

“What have I to lose?” he had asked the inquirer.  “A lot of old lumber which I have accumulated during many years, and a reputation for being wealthy, due to my lonely habits and to the ignorance of those who live around me.”

Durham, mentally reviewing the words of the report, reconstructed the scene in his mind; and now, having come to the end of the lane where the iron post rested, he stood staring up at a place in the ancient wall where several bricks had decayed, and where it was possible, according to the statement of the man Poland, to climb up on to a piece of sloping roof, and thence gain the skylight through which Cohen had obtained admittance on the night of his death.

He made sure that his automatic pistol was in his pocket, questioned the dull sounds of the riverside for a moment, looking about him anxiously, and then, using the leaning post as a stepping-stone, he succeeded in wedging his foot into a crevice in the wall.  By the exercise of some agility he scrambled up to the top, and presently found himself lying upon a sloping roof.

The skylight remained well out of reach, but his rubber-soled shoes enabled him to creep up the slates until he could grasp the framework with his hands.  Presently he found himself perched upon the trap which, if his information could be relied upon, possessed no fastener, or one so faulty that the trap could be raised by means of a brad-awl.  He carried one in his pocket, and, screwing it into the framework, he lifted it cautiously, making very little noise.