The car rolled smoothly towards Fleet Street, but no inspiration came to her. She alighted at the advertisement office, with its plate glass and gilded letters, and was attended by an obsequious clerk. Outwardly calm, but with her heart beating quickly beneath her furs, she put her inquiry to a sleek-haired clerk. He was polite but firm. It was quite possible that such an advertisement as she mentioned had been sent for insertion the following day, and again it might not. In any case he was forbidden to give any information. It would be quite out of the question to stop any advertisement unless she held the receipt. "But if the advertisement has not already been given in, can you give a note to whoever brings it?" she asked, in a flash of inspiration. "Yes, that could be done." She tore off her glove, and with slim, nervous fingers wrote hurriedly. The sleek clerk supplied her with an envelope, and as she placed her message in it and handed it to him she felt it was a forlorn hope. There was only one other way of outwitting the detectives. Should Grell give any address in his message, she must reach him early in the morning before the police could act. A couple of questions elicited the fact that the paper would be on sale by four the next morning. That would mean another journey to Fleet Street, for the ordinary news-agents' shops would not be open at that time. The brougham turned about and began the homeward journey. A respectably dressed working man, who had apparently been absorbed in a page of advertisements of situations vacant displayed on a slab in the window, slouched into the office, and a man bareheaded and wearing a frock-coat moved briskly forward, apparently to attend to him. Yet it was more than coincidence that they met at a deserted end of the counter. "That was Lady Eileen Meredith," said the workman, in a quick, low voice. "What did she want?" "She's guessed that we know the cipher," retorted the other. "She gave a letter to be handed over to whoever brings the advertisement. Here is what she says." He pulled the letter which Eileen had written five minutes before from its envelope: "'The police know the cipher. Be very cautious. R. F. is acting with them.' I'll telephone to Mr. Foyle at once. You had better stay outside." The second man went back to the pavement and resumed his study of the advertisement board, but a close observer might have seen that his eyes wandered past it now and again to the persons inside the office. Half an hour went by. Then the frock-coated man inside took a silk hat from a peg and placed it on his head. Simultaneously a woman went out. A dozen paces behind her went the workman, and a dozen paces behind him the frock-coated man.