Quaid followed, regretting that only her helmet was translucent. Even so, it was a pleasure to watch her walk. She led him to a tortured opening in the side of the mountain, evidently a fault that had sprung during one of the eruptions. It was a cave whose walls were sheer. Just enough light filtered in through crevices to enable them to find secure footing as the passage wound into the mountain.

They came to a ledge deep inside. They were in a roughly circular chamber of considerable size. No, it was a depression, a hole; the sky of Mars showed above. Its floor was a pit so deep that it seemed to have no bottom. Quaid’s eyes, adapting to the deep shade at this level, made out only the curving rim and the cylindrical rise of the rock above. Was this a natural cavity or a chamber hewn by man? It had aspects of both, and neither. He felt an awe of it that related only partly to its size and mystery. Somehow he knew that the significance of the place transcended anything any ordinary man or woman might compass, and that what the two of them did here was more important than anyone on Earth could guess.

The woman walked to the right. She reached down and drew out a slender cable. It seemed to be anchored to a large rock or projection from the wall. She backed away, hauling on the cable, and it extended. She turned, and Quaid saw that the end she held was connected to an apparatus somewhat like a fishing reel mounted on a solid belt.

She brought this belt to him and stretched out its ends. She bent to reach around his waist, wrapping the belt until it snapped together behind him. Now the reel was in front, and he was tied to the rock.

Quaid tested it himself, stepping back and watching the cable pay out. It was coiled within the reel, flattening there but becoming round as it reached toward the rock anchor. There was actually a considerable length of it, but it weighed only a few pounds.