"They'll come up through the tunnels into the old city, spread out, and attack the camp at night." Nick looked thoughtful. "What difference does it make?" Susan asked. "They'll all be killed on the charged barrier, if the proton cannon let them get that far. They can't win." "Maybe," was all Nick could reply. The heat grew unbearable, and several times during the long morning they were forced to change position to remain in the shade. They moved as little as possible, saving their energy and conserving their precious body water by avoiding any exertion that would bring on sweating. Only Klev remained in the sun, his alien body gratefully soaking up the harsh rays. Occasionally he moved, each motion bringing a half suppressed mew of pain to his lips. "How bad?" Nick asked. Susan shook her head. "He says he will be all right, but that swelling Merlo's varlu made near his eye looks serious. His leg is badly hurt, and he's terribly old, Nick." By midafternoon their faces were flushed and dry, and the powder-fine sand itched intolerably where it had sifted into their clothing. Susan napped, but stirred restlessly and muttered of water. "Sue," Nick asked when she opened her eyes. "Is Klev in shape to talk sense?" The Martian saw his glance and chirped affirmatively, then clamped his thin lips to smother an exclamation of anguish. "Ask him if the passage through which they brought us up connects with any of the water caverns you mentioned." She looked at him inquiringly. "Might as well be killed by the Martians as die of thirst. Ask him." Sue talked to the Martian, who nodded and began to trace a complicated diagram in the sand with one finger, hesitating before adding each line as though resurrecting old and almost forgotten memories. Nick watched a while. Then a patrol rocket whistled over heading south, and after it had passed he climbed once more to the rim of the bowl. He watched it settle inside the barrier with a flare of braking jets and a cloud of red dust. And while he watched he