Ladd pursued a zigzag course southward across the desert, trotting down the aisles, cantering in wide, bare patches, walking through the clumps of cacti. The desert seemed all of a sameness to Dick--a wilderness of rocks and jagged growths hemmed in by lowering ranges, always looking close, yet never growing any nearer. The moon slanted back toward the west, losing its white radiance, and the gloom of the earlier evening began to creep into the washes and to darken under the mesas. By and by Ladd entered an arroyo, and here the travelers turned and twisted with the meanderings of a dry stream bed. At the head of a canyon they had to take once more to the rougher ground. Always it led down, always it grew rougher, more rolling, with wider bare spaces, always the black ranges loomed close. Gale became chilled to the bone, and his clothes were damp and cold. His knees smarted from the wounds of the poisoned thorns, and his right hand was either swollen stiff or too numb to move. Moreover, he was tiring. The excitement, the long walk, the miles on miles of jolting trot--these had wearied him. Mercedes must be made of steel, he thought, to stand all that she had been subjected to and yet, when the stars were paling and dawn perhaps not far away, stay in the saddle. So Dick Gale rode on, drowsier for each mile, and more and more giving the horse a choice of ground. Sometimes a prod from a murderous spine roused Dick. A grayness had blotted out the waning moon in the west and the clear, dark, starry sky overhead. Once when Gale, thinking to fight his weariness, raised his head, he saw that one of the horses in the lead was riderless. Ladd was carrying Mercedes. Dick marveled that her collapse had not come sooner. Another time, rousing himself again, he imagined they were now on a good hard road.