Thin electric flex descended from somewhere inside the case down one of the legs of the pedestal, and through a neatly drilled hole in the floor, evidently placed there to accommodate it.

“Burglar alarm!” he muttered.

The opening of this case, and doubtless of any of the others, would set alarm bells ringing.  This was not an unimportant discovery, but it brought him very little nearer to a solution of the chief problem which engaged his mind.  Assuming that Cohen had opened one of the cases and had alarmed old Huang Chow, what steps had the latter taken to deal with the intruder which had resulted in so ghastly a death?  And how had he disposed of the body?

As Durham stood there musing and looking down through the plate-glass at the delicate porcelain beneath, a faint sound intruded itself upon the stillness.  It gave him another idea.  Part of the floor was stone-paved, but part was wood.

Upon a portion of the latter, where no carpet rested, Durham dropped flat, pressing his ear to the floor.

A faint swishing and trickling sound was perceptible from some place beneath.

“Ah!” he murmured.

Remembering that the premises almost overhung the Thames, he divined that the cellars were flooded at high tide, or that there was some kind of drain or cutting running underneath the house.

He stood up again, listening intently for any sound within the building.  He thought he had detected something, and now, as he stood there alert, he heard it again—­a faint scuffling, which might have been occasioned by rats or even mice, but which, in some subtle and very unpleasant way, did not suggest the movements of these familiar rodents.

Even as he perceived it, it ceased, leaving him wondering, and uncomfortably conscious of a sudden dread of his surroundings.  He wondered in what part of this mysterious house Lala resided, and recognizing that his departure must leave traces, he determined to prosecute his inquiries as far as possible, since another opportunity might not arise.

He was baffled but still hopeful.  Something there was in the smell of the place which threatened to unnerve him; or perhaps in its silence, which remained quite unbroken save when, by acute listening, one detected the dripping of water.

That unexplained scuffling sound, too, which he had failed to trace or identify, lingered in his memory insistently, and for some reason contained the elements of fear.

He crossed the room and began softly to mount the stair.  It creaked only slightly, and the door at the top proved to be ajar.  He peeped in, to find the place empty.  It was a typical Chinese apartment, containing very little furniture, the raised desk being the most noticeable item, except for a small shrine which faced it on the other side of the room.

He mounted the steps to the desk and inspected a number of loose papers which lay upon it.  Without exception they were written in Chinese.  A sort of large, dull white blotting-pad lay upon the table, but its surface was smooth and glossy.