As the horses started up, Dorothy refuted Tom’s statement indignantly. “It isn’t a blind alley. It’s a good clue. We’ve run down practically every other line, and now we may as well try this. Everything points to the belief that ‘the man’ is a scientist of no slight ability. Whether he or some one else discovered his high power radio-active force, he must be a good man, or he wouldn’t be able to use it. Now, it seems probable to me that he was working with phosphorescent ink simply because it was the nearest at hand. A man engaged in research like that would be likely to have at least one assistant. I propose to find that assistant.” “I’d like to see you do it,” said Tom doubtingly. “How would you go to work?” “I’d advertise,” said Dorothy. “Advertise,” remarked Tom. “Here’s the way to do it,--‘Wanted, the assistant of the man who is trying to stop all war.’” “Of course not, stupid,” said Dorothy impatiently. “We’ll advertise for a man who has had some experience in making phosphorescent ink. That’s the line to work on. Don’t you see that since phosphorescent paint acts best with such energy as is given by radio-active substances, that he’s likely to have been using it. There’s such a close relation between phosphorescence and radioactivity, that a man might be working with both.” “But where will you advertise?” I said. “How can you tell where the man has worked? How can you tell his nationality? I think he is an American, but no one can tell.” “If you mean Dick Regnier,” exclaimed Dorothy, her eyes flashing, “you’re wrong. I’ve known him for years, and I know he is not the man. It takes just a touch of insanity that Dick never had, to do what ‘the man’ is doing. ‘The man’ must be practically a monomaniac on the subject.” The bus stopped just as the Bank came in sight. Dorothy turned squarely in her seat and faced me. The seats around us happened to be empty. She looked at my somewhat guilty face and spoke emphatically. “Jim Orrington, you don’t believe me, but it isn’t Dick Regnier.” “Now, Dorothy,” I said, “look here. How did the letter get changed, unless it was done by Regnier that night at your cousin’s?” “I don’t know,” she answered. “Oh, come now,” said Tom. “Drop it. Here’s where we get off.” We had drawn our money and had started away, when I suddenly thought of the mail. I turned back to the little window and asked if there were any letters for us which had not been forwarded. A few moments brought a big package, among them three or four bulky envelopes from the office. Hailing a cab, we read busily as we drove back to the Savoy. One long typewritten report I read with especial care, and handed over to Dorothy when she had finished her mail. She looked at me reproachfully, as she read the title. “And you never mentioned this at all.”