"I see." The simplicity of it at once dawned on him. "That was what Foyle meant when he said that some ciphers could not be solved by the recurring E," he said unthinkingly. She had risen and flung away from him in quick revulsion. One glance at her face told him what he had done. "You spy!" There was stinging scorn in her tone. "You have talked it over with Foyle, and that man knows all. You are here to worm out what I know in order to betray your friend. Oh, don't trouble to lie,"--as he would have spoken,--"I can see your object. And I nearly fell into the trap." The man was not without dignity, as he stood a little white but steady. "You may call me what you like," he said in a low voice. "Spy, if you will. Believe me or not, I have acted for the best, for you and for Grell. You once called me a murderer--with what justification you now know. Are you so ready to judge hastily again?" If he had hoped to move her from her gust of passion, he quickly learned his mistake. Her lips curled in contempt, and, drawing her skirts aside as she passed him as though a touch might contaminate her, she swept to the doorway. For one instant she stood posed. "You call yourself a spy. It is a good name. For a police spy there is no room in this house." With that she was gone. The man had flushed under the biting contempt in her voice and words, and now stood for a little with hands tightly clenched, gazing after her. He felt that, from her point of view at least, there was some truth in her words. He was--whatever his motives--a police spy. And yet he was but concerned to clear up the horrible tangle in which his friend and the girl had become involved. He did not know that he was watched from behind the curtains as he walked blindly into the street. Eileen, with lips firmly set and face tense, was concealed behind curtains. No sooner had he gone than she hurriedly dressed herself and ordered an electric brougham. She had come to believe that her lover's safety depended on her actions that day. Foyle knew the secret of the cipher, and Grell's advertisement told her that he intended communicating something to her by that method the next day. At all costs she must prevent him betraying himself. Only one course occurred to her. She must go to the office of the _Daily Wire_ and prevent his advertisement from appearing. How she was to do it she had not the slightest idea. That she left for later reflection.