"It is the Night of Power--in the old Egyptian Calendar, you know," he answered with assumed lightness almost, "the final moment of Leyel-el-Sud, the period of Black Nights when the Desert was held to encroach with--with various possibilities of a supernatural order. She wishes to revive a certain practice of the old Egyptians. There _may_ be curious results. At any rate, the occasion is a picturesque one--better than this cheap imitation of London life." And he indicated the lights, the signs of people in the hall dressed for gaieties and dances, the hotel orchestra that played after dinner. Henriot at the moment answered nothing, so great was the rush of conflicting emotions that came he knew not whence. Vance went calmly on. He spoke with a simple frankness that was meant to be disarming. Henriot never took his eyes off him. The two men stared steadily at one another. "She wants to know if you will come and help too--in a certain way only: not in the experiment itself precisely, but by watching merely and--" He hesitated an instant, half lowering his eyes. "Drawing the picture," Henriot helped him deliberately. "Drawing what you see, yes," Vance replied, the voice turned graver in spite of himself. "She wants--she hopes to catch the outlines of anything that happens--" "Comes." "Exactly. Determine the shape of anything that comes. You may remember your conversation of the other night with her. She is very certain of success." This was direct enough at any rate. It was as formal as an invitation to a dinner, and as guileless. The thing he thought he wanted lay within his reach. He had merely to say yes. He did say yes; but first he looked about him instinctively, as for guidance. He looked at the stars twinkling high above the distant Libyan Plateau; at the long arms of the Desert, gleaming weirdly white in the moonlight, and reaching towards him down every opening between the houses; at the heavy mass of the Mokattam Hills, guarding the Arabian Wilderness with strange, peaked barriers, their sand-carved ridges dark and still above the Wadi Hof. These questionings attracted no response. The Desert watched him, but it did not answer. There was only the shrill whistling cry of the lizards, and the sing-song of a white-robed Arab gliding down the sandy street. And through these sounds he heard his own voice answer: "I will come--yes. But how can I help? Tell me what you propose--your plan?" And the face of Vance, seen plainly in the electric glare, betrayed his satisfaction. The opposing things in the fellow's mind of darkness fought visibly in his eyes and skin. The sordid motive, planning a dreadful act, leaped to his face, and with it a flash of this other yearning that sought unearthly knowledge, perhaps believed it too. No wonder there was conflict written on his features. Then all expression vanished again; he leaned forward, lowering his voice.