He did not finish the sentence. Somewhere In that lonely and wild section of Happy Valley a single shot rang out, making the echoes vibrate loudly, and awakening a distant coyote, who sent up a mournful howl. CHAPTER XVIII THE BOILING SPRING "What's that?" asked Bud suddenly, his voice seeming almost as loud as that of Yellin' Kid's. The horses had been reined to a halt as soon as the shot sounded, and there was stillness which made the boy rancher's exclamation appear more vociferous than would otherwise have been the case. "What's that?" asked Bud again. "Some one fired," answered Nort. "Brilliant!" chuckled Dick. "Bright answer!" "Almost as bright as my question," conceded Bud, who was willing to admit when he had "pulled a bloomer," as some Englishmen might term it. "It was a shot, though," he added. "I wonder if we'll hear any more?" They all paused, in listening attitudes; the boy ranchers, the cowboys associated with them in the Happy Valley venture and the others sent with Slim to help run down the rustlers, on whose trail they now were. But no further firing followed in the three or four minutes they waited there in that lonely gorge, the only sounds being those caused by the restless movements of the steeds. "I wonder if some one shot at us, or if that was a signal!" remarked Nort, as Bud gave the sign to advance. "I didn't hear any bullet singin' out this way," drawled Slim. "Not that I'm hankerin' to," he quickly added. "Then it might have been a signal," went on Nort. "What makes you say that?" Bud questioned. "Because it would seem that if the rustlers are ahead of us, trying their best to get far enough away, or to get to some secret hiding place, that they might leave some behind, on the trail, to give warning when we show up," went on Nort. "Yes, that might be so," slowly admitted Bud. "In fact I think it was, probably, a signal, and it may have been given by the same one who gave signals before." "What do you mean?" asked Dick. "I mean Four Eyes, and the lantern flashes we saw from the watch tower that night we rode in," Bud answered. "I believe Four Eyes was and still is, in with the rustlers, and that he gave a signal to show that everything was ready for the raid." "But the raid didn't take place until some time after we saw those flashing lights," said Dick. "It takes some time to get a cattle-rustling gang together," declared Bud. "I wish we could find Four Eyes." His gaze roved the sides of the lonely gorge, and sought to pierce the maze of the trail ahead. But as it wound in and out, following the windings of the defile, he could not see far in that direction. "If it was Four Eyes, he played his game mighty slick!" declared Yellin' Kid. "He fooled us all, includin' your paw, Bud!"