But, though he ranged farther each time, he found nothing, returning after each trip with a sharper fear. Night again found him watching over her worriedly, listening to her dry, hacking cough. Her lips were cracked and swollen. He was vaguely surprised to find his own lips split so that one was bleeding. And on his last scouting trip he had stumbled badly. A low grade had exhausted him. His strength was waning. They could not live long without water. The human trail they had followed for two days must surely lead to help, to a source of food and water. But time was running out on them. Should he keep following the tracks, or strike out across the foothills, searching for a stream? He didn't know, and the uncertainty plagued him through the long night. Falling into fitful sleep, he dreamed of a rushing mountain stream, clear and cold, frothing as it boiled over beds of rock, cold and sweet and nourishing... In the morning Ann seemed stronger. They set off at an easy, careful pace. Hendley helped her when the way was steep, carrying her over the most difficult stretches. They climbed steadily, following the fresh trail. When she could go no farther, he lifted her across his shoulders and went on, laboring. They made little progress. At noon he had to rest. Because the day was cloudy and cool, with a stiff cutting wind whining through the gullies and bending the grasses that covered the foothills. Hendley searched carefully for a sheltered cove. He knew they had gone almost as far as they could go. Alone he might have struggled on for another day, perhaps more. But he would not leave her to save himself. After a brief rest he made one more fruitless search for water. Exploring a ravine which looked promising, a slash across the hills once carved by a river but now dry, he was gone longer than he had intended. When he returned, he found Ann sprawled on the ground, only half-conscious. They were absolutely alone in the vast, empty land. To the east now there was only an endless reach of denuded prairie. The towers of the city were no longer visible. The only sign of human existence other than themselves was the tauntingly recent trail they had been following. What men were these? Where did the tracks lead? How far? He felt again the sense of being cheated, of a promise made, a hope nurtured, which could not be fulfilled. Shortly after dusk he heard the buzz of an aircraft overhead, but he could not find it. This remote sign of life quickened no hope. The blind copters droning across the sky carried no one who could, or would, save them. Ann came out of her delirium to stare at him. Her eyes were large, wide open, unexpectedly lucid. "You must go on without me," she said calmly. "You can make it without me." He shook his head. "There is nothing without you." "You could find help--come back for me." "No, Ann," he said gently. "We have to face it. There is no help. And I won't leave you alone."