Some four feet from the bottom of the blind (or five feet from the floor) a piece of linen a foot square had been neatly slashed out!

I glanced around the room.  Several fashionably dressed visitors were looking idly in our direction, but I could fasten upon no one of them as a likely perpetrator.

Bristol stared at me in perplexity.

“Who on earth did it,” he muttered, “and what the blazes for?”

CHAPTER XII

THE HASHISHIN WATCH

“The American gentleman has just gone out, sir,” said the sergeant at the door.

I nodded grimly and raced down the steps.  Despite my half-formed desire that the slipper should be recovered by those to whom properly it belonged, I experienced at times a curious interest in its welfare.  I cannot explain this.  Across the hall in front of me I saw Earl Dexter passing out of the Museum.  I followed him through into Kingsway and thence to Fleet Street.  He sauntered easily along, a nonchalant gray figure.  I had begun to think that he was bound for his hotel and that I was wasting my time when he turned sharply into quiet Salisbury Square; it was almost deserted.

My heart leapt into my mouth with a presentiment of what was coming as I saw an elegant and beautifully dressed woman sauntering along in front of us on the far side.

Was it that I detected something familiar in her carriage, in the poise of her head—­something that reminded me of former unforgettable encounters; encounters which without exception had presaged attempts upon the slipper of the Prophet?  Or was it that I recollected how Dexter had booked two passages to America?  I cannot say, but I felt my heart leap; I knew beyond any possibility of doubt that this meeting in Salisbury Square marked the opening of a new chapter in the history of the slipper.

Dexter slipped his arm within that of the girl in front of him and they paced slowly forward in earnest conversation.  I suppose my action was very amateurish and very poor detective work; but regardless of discovery I crossed the road and passed close by the pair.

I am certain that Dexter was speaking as I came up, but, well out of earshot, his voice was suddenly arrested.  His companion turned and looked at me.

I was prepared for it, yet was thrilled electrically by the flashing glance of the violet eyes—­for it was she—­the beautiful harbinger of calamities!

My brain was in a whirl; complication piled itself upon complication; yet in the heart of all this bewilderment I thought I could detect the key of the labyrinth, but at the time my ideas were in disorder, for the violet eyes were not lowered but fixed upon me in cold scorn.

I knew myself helpless, and bending my head with conscious embarrassment I passed on hurriedly.