The baronet found the girl waiting for him, her face alight with eagerness. She was in her own boudoir, luxuriously ensconced in a big arm-chair, and she smiled brightly at him--such a smile as he had not seen since before the murder. He obeyed her invitation to sit down.

"You wanted to see me alone," he said.

She nodded. "Yes, I want to know if we are allies--or enemies. I know I have treated you abominably, but I was driven half mad by the thought that Bob was dead. Now we are working together--are we not?"

He made a little gesture with his hands, helplessly as one at a loss.

"In so far as we both wish to get Grell out of his difficulty--and I wish I knew what that was--yes," he replied. "I don't believe him to be a murderer, but why does he remain in hiding? He is not the sort of man to do foolish things, and that is foolish on the face of it. He has some strong reason for being out of the way. Can you explain?"

She pulled her chair closer to him, and laid one slim hand on his.

"I cannot explain--I can only trust. He looked to us to help him. I know that he wants money, for he sent a friend to tell me. I had none, but I gave her my jewels. Detectives were watching her, and they, with the connivance of my father, took them from her. Now, you, his most intimate friend, must help him. He has given you the key to the cipher which will appear, and then, I suppose, he will tell you how to get it to him."

She had apparently taken it for granted that the baronet was with her in whole-souled devotion to her lover. His fingers beat a tattoo on his knee.

"So that advertis.e.m.e.nt was the key to a cipher? Do you know when I shall get a message?"

"I shall get one to-morrow. You--who knows?"

"Then you can tell me how to read it?"

She hesitated a moment, finger on chin. Then, animated by a quick resolve, she moved to a little inlaid desk and unlocked a drawer. She returned with a piece of paper in her hand.

"What was the number mentioned in your advertis.e.m.e.nt?"

"2315."

For a little the only sound in the room was the scratching of pencil on paper. At last she finished, and handed the result to him. He wrinkled his brows as he studied it.

THIS IS THE KEY 2315 23 152 315 VKJX KV UMG NFD

"The bottom line is the top one turned into cipher," she explained. "The middle line is the key number. In the first word you take the second letter from T, the third from H, the first from I, and so on. It is a cipher that cannot be unravelled without the key number. H becomes K once and M once."

"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 pa.s.sion, he quickly learned his mistake. Her lips curled in contempt, and, drawing her skirts aside as she pa.s.sed 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 advertis.e.m.e.nt 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 advertis.e.m.e.nt from appearing. How she was to do it she had not the slightest idea. That she left for later reflection.

The car rolled smoothly towards Fleet Street, but no inspiration came to her. She alighted at the advertis.e.m.e.nt office, with its plate gla.s.s 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 advertis.e.m.e.nt 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 advertis.e.m.e.nt unless she held the receipt.

"But if the advertis.e.m.e.nt 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 advertis.e.m.e.nts 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 advertis.e.m.e.nt. 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 advertis.e.m.e.nt 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.

Heldon Foyle had selected his subordinates well for their work. Acting on the policy of leaving nothing to chance, he had taken a hint from the advertis.e.m.e.nt addressed to Eileen, and had the office watched from the time it opened. It was simple to get the manager's permission to place one man within, and to get him to direct the clerks to pa.s.s through his hands all cipher advertis.e.m.e.nts for the personal column. If the advertis.e.m.e.nt came through the post, their time would be thrown away. If it was delivered by hand, there was a chance of learning whence it had been dispatched. The intervention of Lady Eileen was an accident that could not have been foreseen. In that matter luck had played into Foyle's hands.

CHAPTER x.x.x

Between Berkeley Square and Scotland Yard, Fairfield consumed ten cigarettes in sharp jerky puffs. Yet he was scarcely conscious of lighting one. Indeed, as he climbed the wide flight of steps at the main entrance, it seemed as though no palpable interval of time had elapsed since he had been practically turned out of her father's house by Eileen Meredith.

Heldon Foyle put away the bundle of doc.u.ments that contained the history of the case as the baronet was announced, and waved his visitor to a chair.

"Well?" he asked.

Fairfield shrugged his shoulders. "A nice mess you've got me into," he complained. "Why didn't you tell me you knew the secret of the cipher?"

The detective's face was full of ingenuous surprise as he answered--

"Didn't I? I thought I made it perfectly clear to you. I am sorry that you misunderstood. I should have made it plainer. What has gone wrong?"

Sir Ralph made an impatient gesture. "Oh, what's the use of talking nonsense? You did not tell me that you knew the cipher, and as a consequence Lady Eileen now knows that you know."

The superintendent gave no indication of the chagrin with which the news filled him. His features were perfectly expressionless. A part of his plans had failed from excess of caution. He did not need Fairfield to tell him what had happened. He could make a fairly accurate guess as to the manner in which he had been unwittingly betrayed. His thoughts turned at once to the question of what the girl would do. If he had judged her right, she would try to warn Grell. Either she knew his address or not, but it was unlikely that she did, as they were communicating in cipher. The obvious thing for her to do was to try to stop the advertis.e.m.e.nt. There was, however, little he could do. He had men on duty in Berkeley Square and in Fleet Street. He would soon hear of any new developments.

"That's a pity," he said reflectively. "It may mean a re-arrangement of our plans. And believe me, Sir Ralph, I badly regret now that I did not go into fuller details with you. What happened?"

Stumblingly, Sir Ralph recapitulated the scene at Berkeley Square, giving even the epithets by which the girl had addressed him. Foyle tapped lightly on his desk with the end of a penholder. The event had been as he thought. He looked Sir Ralph straight in the eye.

"She told you that you were a spy--that I had used you as a tool," he said sharply. "You have been hurt by her words. I don't want you to feel that you are anything but a free agent, or to do anything that you consider dishonourable. But I must know whether you are still willing to act with us, or whether you wish to stand aside."

Fairfield threw the stump of cigarette viciously into the fire.