"The moon is high, and whilst all the side of the hotel is in shadow the acacia is in the moonlight. Its branches would afford concealment, however; and one watching there could see what would be hidden from one on this balcony. I request you, Kernaby Pasha, to approach that _lebbekh_ tree from the further side of the fountain, in order to remain invisible from the hotel. Climb to one of the lower branches, and closely watch four windows." I stared at him in the darkness. "Which are the four windows that I am to watch?" "They are--one, that immediately below your own; two, that to the right of it; three, the window above the Harêm Suite; and, four, the extreme east window of this wing, on the first floor." Now, my state of mystification grew even denser. For the windows specified were, in the order of mention, that of Inspector Carlisle, who had not yet recovered consciousness; of Mr. Chundermeyer; of Major Redpath, a retired Anglo-Indian who had been confined to his room for some time with an attack of malaria; and of M. Balabas, the manager. "For what," I inquired, "am I to watch?" "For a man to descend." "And then?" "You will hold your open watch case where it is clearly visible from this spot. Instant upon the man's appearance you will cover it up, and then uncover it, either once, twice, thrice, or four times." "After which?" "Remain scrupulously concealed. Have the collar of your dinner jacket turned up in order to betray as little whiteness as possible. Do not interfere with the man who descends; but if he enters the Harêm Suite, see that he does not come out again! There is no time for further explanation, Kernaby Pasha; it is Omar of Ispahân with whom we have to deal!" V Perched up amid the foliage of the acacia, I commenced that singular guard imposed upon me by Abû Tabâh. Did he suspect one of these four persons of being the notorious Omar? Or had his mysterious instructions some other significance? The problem defied me; and, recognizing that I was hopelessly at sea, I abandoned useless conjecture and merely watched. Nor was my vigil a long one. I doubt if I had been at my post for ten minutes ere a vague figure appeared upon the shadow-veiled balcony of one of the suspected windows--that of Major Redpath, above the Harêm Suite! Scarcely daring to credit my eyes, I saw the figure throw down on to the projecting top of the _mushrabîyeh_ window below a slender rope ladder. I covered the gleaming gold of my watch-case with my hand, and gave the signal--_three_. The spirit of phantasy embraced me; and, unmoved to further surprise, I watched the unknown swarm down the ladder with the agility of an ape. He seemed to wear a robe, surely that of the _Veiled Prophet_! He silently manipulated one of the side-panels of the window, opened it, and vanished within the Harêm Suite.