"Why, he was brought in a few nights since by our man who watches the rivermen. They're a rough, bad lot. He found this man on a carouse in one of their haunts. Showing all kinds of money. He watched them, and jumped in just as they attacked the man and were about to rob him. We found over twenty thousand dollars in bank notes on the man--think of that! Only once since then has he entirely recovered from that cut on his head, and refused to give his name or say a word, except that his money came from a gold mine." "Yes, a gold mine on wheels," observed Zeph pointedly. "The man's mind is affected by the blow he got, and only a few minutes at a time has he been rational. He offered me all his money if I'd let him go. Funny thing, though; in one of his spells early this morning I found him whispering to old Palmer." "Did you?" pressed Zeph eagerly. "The old man ain't right, you know, but he sticks to that click-clack contrivance all the time. I watched the two, and the prisoner promised Palmer all kinds of things if he'd get free and send a certain message to a certain party, or somehow get the telegram sent. Well, since then the old man has been terribly busy with his play telegraph device, and excited, too. About an hour since he calls me to him, and says he will certainly get me a thousand dollars if I will take a message to the operator here. Only ten words, he says--one hundred dollars a word. I told him I wouldn't do anything until the sheriff came back tomorrow. He said only ten words. I asked him what ten words, and he shot out a lot of gibberish I couldn't take in." "A cypher telegram," murmured Zeph. "Well, I left it that way." "Let me lurk around a bit, will you?" inquired Ralph. "Certainly," assented the marshal. For the next ten minutes Ralph, hidden in a corner of the detention room, posted himself and listened. When he came out his face was excited and eager. "Don't let those prisoners send out a word or see a single person until I come back to you," he directed the marshal. "All right. Found out something?" "I think I have. I'll know for sure inside of six hours." "And let me know, too. You see all this bothersome mystery is worrying me." "You first of all," declared Ralph, "and you won't lose by coöperating with us." "I see you're smart boys," observed the inexperienced marshal, "and I trust in your word to straighten out this tangle." "What, Ralph?" broke in Zeph eagerly, as they left the place. "I think I've got the clew." "To what?" "The whole pay car business--at least the start of one." "Tell me about it."