Such was the fact, and the knowledge came to the friends in the most startling manner conceivable, being in the shape of several rifle bullets which whistled about their ears. Then, when they glanced affrightedly around, they saw fully a dozen Sioux bucks, all well mounted, bearing down upon them at full speed. They had issued from the rocky section behind them, and ridden to this perilous position without the youths once dreaming of the fact until, as may be said, the hostiles were literally upon them. CHAPTER XX. A RUN FOR LIFE. But one thing could be done: that was to run, and Warren Starr and Tim Brophy did it in the highest style of the art. They put their ponies to their utmost pace without an instant's delay. The animals, as if conscious of their peril, bounded across the snowy plain on a dead run, with their riders stretching forward over their necks to escape the bullets expected every moment. It must have been that the Sioux were sure the fugitives would look around the next moment, else they would have stolen nearer before announcing their presence in such a startling fashion. The only hope for the young ranchers lay in the speed of their horses, since there was no other possible chance against the bucks who were as fierce after their lives as so many ravening wolves. The boys shouted to their animals, who flew across the plain as though the snow did not discommode them in the least. They did not separate, for the instinctive resolve thrilled them that they would fall or escape together. Each was provided with a repeating Winchester, and enough has been told to prove they knew how to use the weapons effectively, but the opportunity was hardly the present, since to turn and fire while their ponies were on the run, offered little chance of success, and was liable to interfere with their speed, so important above everything else. The flight was so sudden that, without thought, they headed toward the wooded ridge, where they had seen the suspicious signal fire, but they had not gone far before discovering that that would never do. The flight must end at the ridge, where they would find themselves at fearful disadvantage. "We must have the open plain or we are lost!" called Warren. "Ay, ay; I'm wid ye," replied Tim, who pulled sharply on the right rein of his animal. At the same moment his friend turned the head of his horse to the left, and, before the comrades were aware, they were diverging with several rods between them. Warren was the first to perceive the mistake, and believing he had adopted the right line of flight, shouted for his friend to do the same. Tim had already noticed the turn and now thundered across the prairie toward him. But the devious course, as will be readily seen, threw him slightly to the rear, seeing which, Warren drew in his animal to allow him to come up. "None of that!" called the Irishman; "ye've no advantage to throw away! Ye can't hilp me by that nonsense."