Who was this who seemed to be warning him, as well as threatening him? Was it a fake, or in earnest? Were the strikers or their friends trying to frighten him? Or did somebody who really felt kindly toward the young engineer believe that he should be warned of a real danger? And where had he seen that handwriting before? This last question seemed as important as the others. After the blowing out of the trestle pillar at the Devil’s Den, Ralph could easily believe that Andy McCarrey’s crowd would attempt other wicked designs against the peace and safety of the road and its loyal employees. That the malcontents were making a grave mistake was undoubtedly a fact. The outrage at Devil’s Den and further attempts to wreck trains on the division would arouse the antagonism of the Brotherhoods instead of bringing their membership into line, as McCarrey had hoped. Such attempts threatened the lives of the train crews. Engineers and firemen and conductors and brakemen could not be frightened into aiding McCarrey in his wildcat strike. That went without saying. Ralph had very little time to decide what he should do about this paper that he had found under his bench. He glanced up at the clock. Three minutes of midnight! But as his gaze fell to the platform again he saw the tall figure of Mr. Adair hurrying along beside the train. Ralph leaned farther out of the window and beckoned him. “What do you want, Ralph?” asked the chief detective hastily, as he leaped up the steps of the locomotive. “I have just heard——” “And I’ve just found _this_.” The young engineer told him where. “And I believe I’ve seen that writing before.” “Whose is it?” demanded Adair the instant he had scanned the warning words. Ralph leaned closer to his ear and whispered a name. Adair started. “No?” he cried. “Do you believe that?” “Compare it with that paper Zeph gave you,” urged Ralph. The gong sounded. The young engineer’s hand went to the throttle. The conductor shouted “All aboard!” “Keep your eyes open, Ralph,” advised the chief detective, swinging himself down. “That is no idle threat. I am going to keep the wires hot ahead of the Midnight Flyer to-night. Never mind if you smash your schedule all to flinders. Safety first, my boy.” “That is not the super’s motto,” said Ralph, rather sharply. “‘Get her through,’ is what he wants.” “You should worry!” exclaimed Adair as the great drivers began to turn. “The G. M. is behind you. I am having the whole division watched. I’ll jack the boys up right now. But if anything happens——” His voice trailed off into silence. At least it was drowned by the exhaust. The express rumbled out from under the train shed and Ralph eased her through the yards. “Due for a bump to-night.” If that warning was serious, it was well worth Ralph Fairbanks’ attention.