He swung in a circle. Dipping into the hollow at a slow walk, he pulled up. In that swale strange marks showed. The grass was pressed flat in swaths less than three feet wide, as if heavy objects had been dragged or rolled across the surface. He got down, bent to examine these peculiarities, and then walked on, leading his two horses, while he conned the ground. So moving, he came to a patch of prickly pear. Stooping, he examined the crushed spiny leaves. A squinting look brought wrinkles between his eyes. “Huh!” he grunted. Then he mounted and followed the marks at a trot. As the crow flies, the flattened swaths ran straight for the burning lignite, where the blue vapors drifted, and it was no great distance to the place. He halted a few yards short of a crevice with ragged edges. Twenty feet on either side the grass had perished long ago. Charlie dismounted and approached with caution. To have the ground break at the lip under his feet meant that he would perish, like a fly cast in a camp fire. The opening, narrow and fairly deep, gave off fumes and smoke, like the breath of some uneasy subterranean monster. Now and then an upward whiff of gas ignited and burned with a wavering flame. Anything dropped in that crevice was utterly beyond rescue. The marks that Charlie followed ran up to the brink, which proved solid earth when he stamped cautiously. Hoofprints and boot marks appeared, with disturbed places in the powder-dry soil. A few broken places showed where comparatively weighty objects had been pushed over the edge. And that was all he could see. Charlie stood a few minutes staring thoughtfully. He frowned into the pit. Few signs, but highly significant ones to him. Queer. Then he mounted his horse and back-tracked. He partly guessed what had made that whispering sound in the night. Now he desired to disprove or verify that guess. That was what he had in mind when he loped back to where he took up this trail. By the bend of the grass blades he knew they had been dragged up that swale. Where there was an end, there must be a beginning. Charlie made a bet with himself that these marks would begin somewhere near the spot from which those shots had been fired at him. He won his bet. The narrow swaths lay along the draw. The depression narrowed, then deepened. Charlie remembered then that a soak spring seeped out of a bank down there, affording water to a hundred head or so of stock. He recalled something else. Three years earlier a horse outfit had located on that spring and built a small corral there, part sod, part poles. Then they had abandoned the place for a better one, forty miles east. He came around a low shoulder of hill. The old corral still stood. It was still in fair shape, and it had been in use. That was plain enough. The marks he had followed began at the gate. The loose dust on the floor was trampled. And from just outside the gate the tracks of a wagon led away northward.