When the butler had brought it, the young man began to regret the Racquet Club less violently. "It's horribly cold out," he said. "There's scarcely a soul on the streets." She nodded brightly: "It's a wonderful night for what we have to do. And I don't mind the cold very much." "Are you proposing to go OUT?" he asked, alarmed. "Why, yes. You don't mind, do you?" "Am _I_ to go, too?" "Certainly. You gave me only twenty-four hours, and I can't do it alone in that time." He said nothing, but his thoughts concentrated upon a single unprintable word. "What have you done with the original Lauffer letter, Mr. Vaux?" she inquired rather nervously. "The usual. No invisible ink had been used; nothing microscopic. There was nothing on the letter or envelope, either, except what we saw." The girl nodded. On a large table behind her chair lay a portfolio. She turned, drew it toward her, and lifted it into her lap. "What have you discovered?" he inquired politely, basking in the grateful warmth of the fire. "Nothing. The cipher is, as I feared, purely arbitrary. It's exasperating, isn't it?" He nodded, toasting his shins. "You see," she continued, opening the portfolio, "here is my copy of this wretched cipher letter. I have transferred it to one sheet. It's nothing but a string of Arabic numbers interspersed with meaningless words. These numbers most probably represent, in the order in which they are written, first the number of the page of some book, then the line on which the word is to be found--say, the tenth line from the top, or maybe from the bottom--and then the position of the word--second from the left or perhaps from the right." "It's utterly impossible to solve that unless you have the book," he remarked; "therefore, why speculate, Miss Erith?" "I'm going to try to find the book." "How?" "By breaking into the shop of Herman Lauffer." "House-breaking? Robbery?" "Yes." Vaux smiled incredulously: "Granted that you get into Lauffer's shop without being arrested, what then?" "I shall have this cipher with me. There are not likely to be many books in the shop of a gilder and maker of picture frames. I shall, by referring to this letter, search what books I find there for a single coherent sentence. When I discover such a sentence I shall know that I have the right book." The young man smoked reflectively and gazed into the burning coals. "So you propose to break into his shop to-night and steal the book?" "There seems to be nothing else to do, Mr. Vaux." "Of course," he remarked sarcastically, "we could turn this matter over to the proper authorities--" "I WON'T! PLEASE don't!" "Why not?" "Because I have concluded that it IS part of our work. And I've begun already. I went to see Lauffer. I took a photograph to be framed." "What does he look like?"