But the conspirators were not eager to go into detail, and their leader said:
"This is a private matter. We are obliged to you gentlemen for trying to stop that boy. But we won't trouble you to ride farther. We are quite able to attend to this business ourselves."
Such an abrupt dismissal, however, only piqued the curiosity of the volunteers the more, and noting this the conspirators clapped spurs to their ponies and soon left them behind.
From time to time, as he raced across the plains, Bob had looked back. With satisfaction, he noted that he more than held his own with the pursuers. But when he saw the four men pass the leaders as though the others were standing still, he urged Firefly to greater speed.
Gamely the pony responded, increasing Bob's lead still more, and the boy noted from landmarks that he was only about two miles from his station. Then suddenly Firefly stumbled, hurling Bob over his head.
Picking himself up, the boy, stopping only to ascertain that he himself was not injured, ran back to his pony. But as he saw the horse his heart sank.
Firefly had stepped in a prairie-dog hole and broken his leg.
From his moaning Bob realized the pony was in great pain, and for a moment he stood undecided what to do. Then a hoarse shout of triumph raised by the conspirators reached his ears, and, gritting his teeth, Bob pulled out his revolver, placed it against Firefly's head and pulled the trigger.
Already he had lost precious minutes and, waiting only to make sure he had put his faithful pony out of misery, he once more started toward his station, leaping and bounding through the high grass as best he could.
Not far had he gone, however, before he realized that unless he could make greater speed, his pursuers would soon overtake him.