Two hundred and forty thousand miles away, Rhoda, descending to the lunar plain, strode rapidly in the direction of the ridge behind which the summit had now disappeared, and, in the course of about twenty minutes, found herself at the foot of a wall of impassable rock which curved unexpectedly and fell away into a vast basin. Turning to retrace her path, she discovered that the peak which she had climbed was no longer visible and that she had lost all sense of direction. To the north, to be sure, her passage was barred, but there was nothing to indicate whether the Ring lay in any one of three directions. Puzzled by the disappearance of the peak, she sprang blindly across the plain, running back on what she fancied was the right course. But the Ring was nowhere to be seen! It had vanished absolutely. And then she recalled the fact that Bennie had told her that the supply of liquid air carried in the cylinders of their vacuum armor would last not much over an hour. Her wrist-watch told her that she had been wandering forty-five minutes. She had only fifteen minutes more in which to find and return to the Ring--a bare quarter of an hour in which she could support life in this hostile environment. A horrible, suffocating death awaited her--was clamped about her head! The sweat started out upon her forehead. Above her head, the escape-valve fluttered feebly, she imagined. What a death! Such a death as Poe might have conceived! Already, she believed that she had some difficulty in breathing. The sunlight seemed dimmer, somehow. Were her ears singing? No; it was only the recurrence of the escape-valve's twitter. She groaned, and the reverberation echoed in the helmet like the roar of a lunar beast. Sick with terror, she turned and scrambled on hands and knees up the rocky sides of the crater until she stood upon the summit of the ridge. There was no sign of the Ring anywhere--only the scarred, spiked plain, with its white sepulchers of rock. Tears of self-pity burned in her eyes; but she could not wipe them away, and they drained down her cheeks and lips into her mouth. They would be looking for her--waiting for her! What agonies would her lover now be suffering, searching that dead, empty plain with his field-glasses for the shadow of the moving thing which meant so much to him!