Detective-Sergeant Sowerby reported himself in Inspector Dunbar's room at New Scotland Yard.

“I have completed my inquiries in Wharf-end Lane,” he said; and pulling out his bulging pocketbook, he consulted it gravely.

Inspector Dunbar looked up.

“Anything important?” he asked.

“We cannot trace the makers of the sanitary fittings, and so forth, but they are all of American pattern. There's nothing in the nature of a trademark to be found from end to end of the place; even the iron sluice-gate at the bottom of the brick tunnel has had the makers' name chipped off, apparently with a cold chisel. So you see they were prepared for all emergencies!”

“Evidently,” said Dunbar, resting his chin on the palms of his hands and his elbows upon the table.

“The office and warehouse staff of the ginger importing concern are innocent enough, as you know already. Kan-Suh Concessions was conducted merely as a blind, of course, but it enabled the Chinaman, Ho-Pin, to appear in Wharf-end Lane at all times of the day and night without exciting suspicion. He was supposed to be the manager, of course. The presence of the wharf is sufficient to explain how they managed to build the place without exciting suspicion. They probably had all the material landed there labeled as preserved ginger, and they would take it down below at night, long after the office and warehouse staff of Concessions had gone home. The workmen probably came and went by way of the river, also, commencing work after nightfall and going away before business commenced in the morning.”

“It beats me,” said Dunbar, reflectively, “how masons, plumbers, decorators, and all the other artisans necessary for a job of that description, could have been kept quiet.”

“Foreigners!” said Sowerby triumphantly. “I'll undertake to say there wasn't an Englishman on the job. The whole of the gang was probably imported from abroad somewhere, boarded and lodged during the day-time in the neighborhood of Limehouse, and watched by Mr. Ho-Pin or somebody else until the job was finished; then shipped back home again. It's easily done if money is no object.”

“That's right enough,” agreed Dunbar; “I have no doubt you've hit upon the truth. But now that the place has been dismantled, what does it look like? I haven't had time to come down myself, but I intend to do so before it's closed up.”