"Oh, I can solve the enigma now," said Ralph with a broader smile than ever. "It is 'S. S.,' by which Zeph means and wants mystified others to half guess means 'Secret Service.' There's one thing about Zeph, with all his wild imaginings and ambition along the railroad line, he sticks to his idea of breaking in somewhere as an active young sleuth." "We think a lot of Zeph, Ralph, and we mustn't forget that he did some bright things in helping that poor little orphan, Ernest Gregg, to health and happiness." "Yes, Zeph deserves great credit for his patience and cleverness in that affair," admitted Ralph warmly, "only the line he is so fascinated with doesn't strike me as a regular business." "How about Mr. Adair, Ralph?" insinuated his mother. "That's so, Bob Adair is the finest railroad detective in the world. If Zeph could line up under his guidance, he might make something practical of himself." "I think he has really done just that." "I am delighted to hear it," said Ralph, and watching the glowing embers in the grate in a dreamy fashion he mused pleasantly over his experience with the redoubtable Zeph, while his mother was busy tidying up the dining room. It was a good deal of satisfaction for Ralph to recall Zeph Dallas to mind. Zeph, a raw country youth, had come to Stanley Junction in a whole peck of trouble. Ralph had always a helping hand for the unlucky or unfortunate. He became a good friend to Zeph and got him a place in the roundhouse. Zeph made a miserable failure of the job. The height of his ambition was to be a detective--like fellows he had read about. Zeph finally landed, as he expressed it, with both feet. The son of a prominent railroad official became interested in hunting up the relatives of a forlorn little fellow named Gregg. He had plenty of money, and he hired Zeph to assist him. The latter showed that he had something in him, for his wit and energy not only located the wealthy relative of the orphan outcast, but upset the plots of a wicked schemer who was planning to rob the friendless lad of his rights. "What did Zeph say about Mr. Adair, mother?" inquired Ralph, as Mrs. Fairbanks again entered the sitting room. "Nothing clear," she explained. "You know how Zeph delights in cuddling up his ideas to himself and looking and acting mysterious. He was very important as he hinted that Mr. Adair depended on him to 'save the day in a big case,' and he said a great deal about a 'rival railroad.'" "Oh, did he, indeed?" murmured Ralph thoughtfully. "Zeph told me to advise you, very secretly he put it, to look out for trouble." "What kind of trouble?" "Particularly, he said, in the train dispatcher's department." "Hm!" commented the young engineer simply, but his brow became furrowed with thought, and he reflected by spells quite seriously over the subject during the evening.