"Stethoscope. Placed the cup on the outside, and then listened to the tumblers as they fell. Simplest thing in the world with an antiquated box like that." "What's missing?" By this time Taylor felt that their positions had been reversed. He, who had come to question, was now on the witness stand, while Madelaine James was doing the cross-examining. But he didn't mind. He knew the way the girl's mind worked, quickly and almost infallibly--her knowledge of women in general and Washington society in particular making her an invaluable ally in a case like this. "A slip of paper some six inches long and two inches wide," he said, with a smile. "The key to the Carruthers Code, probably the most efficient cipher in the world, but now rendered worthless unless the original slip is located before it reaches some foreign power." "Right!" snapped Miss James. "Get busy on your end of the matter. See what you can find out concerning this mysterious woman in the green cloak. I'll work along other and what you would probably call strictly unethical lines. I've got what a man would term a 'hunch,' but in a woman it is 'intuition'--and therefore far more likely to be right. See you later!" and with that she was off toward her car. "But what about your luncheon engagement?" Taylor called after her. "Bother lunch," she laughed back over her shoulder. "If my hunch is right I'll make your chief pay for my meals for the next year!" The next that Taylor heard from his ally was a telephone call on the following evening, instructing him to dig up his evening clothes and to be present at a certain reception that evening. "I have reason to believe," said Madelaine's voice, "that the lady of the second green cloak will be present. Anyhow, there'll be several of your friends there--including myself, Mrs. Armitage, and an ambassador who doesn't stand any too well with the Administration. In fact, I have it on good authority that he's on the verge of being recalled. Naturally we don't want him to take a slip of paper, some six inches by two, with him!" "How do you know he hasn't it already?" "He doesn't return from New York until six o'clock this evening, and the paper is far too valuable to intrust to the mails or to an underling. Remember, I'm not certain that it is he who is supposed to get the paper eventually, but I do know who impersonated Mrs. Prentice, and I likewise know that the lady in question has not communicated with any foreign official in person. Beyond that we'll have to take a chance on the evening's developments," and the receiver was replaced before Taylor could frame any one of the score of questions he wanted to ask. Even at the reception that night he was unable to get hold of Madelaine James long enough to find out just what she did know. In fact, it was nearly midnight before he caught the signal that caused him to enter one of the smaller and rather secluded rooms apart from the main hall.