The brink of the mesa was not far away and so he ambled over to it and had a look down toward the river, which was maybe a hundred meters below. Some patches gleamed and rippled in the moonlight. Others were stamped with the sharp-edged silhouettes of scrubby vegetation growing on its banks and bars. He could hear the purr of a small engine down there, its tone rising and falling as it revved up and down. His revamped ears were pretty good at direction-finding. He swung his head back and forth until he was able to identify the source: just a gray mote angling up the slope below him, cutting its own switchback up the flank of the mesa in a rooster tail of churned-up dust. So at least one vehicle—it sounded, and moved, like an ATV—had survived the flash. And, allowing for switchbacks, it seemed to be headed in his direction.