“Why,” he muttered, “is this one room illuminated—­and all the others in darkness?”

Even then the significance of this circumstance was not apparent to me.  But Harley stared critically at an electric switch which was placed on the immediate right of the door and then up at the silk-shaded lantern which lighted the room.  Crossing, he raised and lowered the switch rapidly, but the lamp continued to burn uninterruptedly!

“Ah!” he said—­“a good trick!”

Grasping the wooden block to which the switch was attached, he turned it bodily—­and I saw that it was a masked knob; for in the next moment he had pulled open the narrow section of wall—­which proved to be nothing less than a cunningly fitted door!

A small, dimly lighted apartment was revealed, the Oriental note still predominant in its appointments, which, however, were few, and which I scarcely paused to note.  For lying upon a mattress in this place was a pretty, fair-haired girl!

She lay on her side, having one white arm thrown out and resting limply on the floor, and she seemed to be in a semi-conscious condition, for although her fine eyes were widely opened, they had a glassy, witless look, and she was evidently unaware of our presence.

“Look at her pupils,” rapped Harley.  “They have drugged her with bhang!  Poor, pretty fool!”

“Good God!” I cried.  “Who is this, Harley?”

“Molly Clayton!” he answered.  “Thank heaven we have saved one victim from Ali of Cairo.”

V

THE HAREM AGENCY

Owing to the instrumentality of Paul Harley, the public never learned that the awful riverside murder called by the Press in reference to the victim’s shaven skull “the barber atrocity” had any relation to the Deepbrow case.  It was physically impossible to identify the victim, and Harley had his own reasons for concealing the truth.  The house on the wharf with its choice Oriental furniture was seized by the police; but, strange to relate, no arrest was made in connection with this most gruesome outrage.  The man who dropped through the trap had been wounded by one of Harley’s shots, and he sank for the last time under the very eyes of the crew of the police cutter.

It was at a late hour on the night of this concluding tragedy that I learned the amazing truth underlying the case.  Wessex was still at work in the East End upon the hundred and one formalities which attached to his office, and Harley and I sat in the study of my friend’s chambers in Chancery Lane.

“You see,” Harley was explaining.  “I got my first clue down at Deepbrow.  The tracks leading to the motor-car.  They showed—­to anyone not hampered by a preconceived opinion—­that the girl and Vane had not gone on together (since the man’s footprints proved him to have been running), but that she had gone first and that he had run after her!  Arguments:  (a) He heard