irn, "I might have come down that staircase
and out by this door without arousing a soul, either by passing
through my own room, or through any other on that floor."

They crossed the yard, where members of the kitchen staff were busily
polishing various cooking utensils, and opened the gate. Dr. Cairn
turned to one of the men near by.

"Is this gate bolted at night?" he asked, in Arabic.

The man shook his head, and seemed to be much amused by the question,
revealing his white teeth as he assured him that it was not.

A narrow lane ran along behind the hotel, communicating with a maze of
streets almost exclusively peopled by natives.

"Rob," said Dr. Cairn slowly, "it begins to dawn upon me that this is
the way I came."

He stood looking to right and left, and seemed to be undecided. Then:

"We will try right," he determined.

They set off along the narrow way. Once clear of the hotel wall, high
buildings rose upon either side, so that at no time during the day
could the sun have penetrated to the winding lane. Suddenly Robert
Cairn stopped.

"Look!" he said, and pointed. "The mosque! You spoke of a mosque near
to the house?"

Dr. Cairn nodded; his eyes were gleaming, now that he felt himself to
be upon the track of this great evil which had shattered his peace.

They advanced until they stood before the door of the mosque--and
there in the shadow of a low archway was just such an ancient,
iron-studded door as Dr. Cairn remembered! Latticed windows overhung
the street above, but no living creature was in sight.

He very gently pressed upon the door, but as he had anticipated it was
fastened from within. In the vague light, his face seemed strangely
haggard as he turned to his son, raising his eyebrows interrogatively.

"It is just possible that I may be mistaken," he said; "so that I
scarcely know what to do."

He stood looking about him in some perplexity.

Adjoining the mosque, was a ruinous house, which clearly had had no
occupants for many years. As Robert Cairn's gaze lighted upon its
gaping window-frames and doorless porch, he seized his father by the
arm.

"We might hide up there," he suggested, "and watch for anyone entering
or leaving the place opposite."

"I have little doubt that this was the scene of my experience,"
replied Dr. Cairn; "therefore I think we will adopt your plan. Perhaps
there is some means of egress at the back. It will be useful if we
have to remain on the watch for an