"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............