In another hour--perhaps before then--the moon would creep over the distant coast range, and bathe the quiet world in silver; until then all hope of pursuit was futile. He stumbled on, groping his way back to the pipe line. Once there, he listened hopefully for some sign, some slight noise that might guide him, but his anxious ears were unrewarded. When at last he returned to the high trail he found only his pony awaiting him. Miss Breen had vanished as suddenly and as mysteriously as had the man she warned. It was quite useless, he knew, to remain where he was. The chances of following the stranger were becoming more and more hopeless. So he climbed into the saddle, and allowed his pony to pick its way slowly and carefully along the trail. What a puzzle this was, to be sure, he reasoned to himself. Undoubtedly the man he had seen, who, thanks to the girl’s warning, had escaped, was none other than the person instrumental in the previous night’s adventure. The fact that he was carrying a sledge hammer gave added proof to this suspicion, to say nothing of his fright at Nash’s abrupt interruption. And yet, what had led Miss Breen to cry out just at the moment when his capture seemed certain? What connection had she with this slinking intruder? Mentally Nash recalled to mind the maps he had stumbled upon; those cleverly executed and highly technical drawings. And how intensely interested she had been in the construction work; what unusual questions she had asked. In spite of this Nash could not bring himself to the point of suspecting the girl of being an accomplice of the man who had committed, or intended to commit, such dastardly outrages. Some of her actions were puzzling, he admitted, and yet she seemed to be cast in too fine a mold for such an association. Upon his return to his cabin, an hour later, Nash found Hooker awaiting him. Hooker came regularly from Los Angeles twice or three times a month, bringing letters and specifications from Sigsbee and the construction board of engineers. “Hello, Nash,” he said. “You’re late to-night. I’ve been waiting since five o’clock.” “I am a bit later than usual,” Nash admitted. “We’ve been troubled with bursted water mains lately. Some vandal has been smashing them with a sledge. I’ve been trying to get at the bottom of the mystery.” Then, as briefly as possible, he told Hooker of the previous night’s accident. Of the recent affair he mentioned not a word. “Nasty business,” answered Hooker. “If it isn’t stopped it’s likely to put you away behind on your contracts. So far, however, Sigsbee is highly elated over your work, Nash. Don’t mind me telling you so, do you? It might seem funny, coming from one in my position, eh? But I’m as glad as the boss. He gave me the same opportunity--and I fell down. Maybe it was the booze, and maybe again it wasn’t. Anyhow, I’m glad to see you’re making good.” “What’s the occasion for to-night’s visit?” Nash asked. “Anything new?”