It was an hour after Fairfield had left her before Eileen Meredith's sobs died away in the deserted room. There was none to hear or see, and she gave way to her grief uncontrolled. Gradually the first shock passed. Her calmness came back to her, but she was a different woman to the vivacious, sunny girl who had looked forward to her wedding-day. Her face was set stonily, and in the grey depths of her eyes there lurked in place of laughter an implacable determination.

She had loved Robert Grell with the fierce, passionate devotion of a strong nature. The sudden news of his death had brought out the primitive woman bent on vengeance. It was no impulse of suddenly shattered nerves that had made her turn on Fairfield. To coldly analyse the facts for and against him was beyond her. She only thought of the man who had a possible motive for slaying her lover and had had a possible opportunity.

Yet none would have guessed the burning emotion that thrilled in her veins as she submitted to the ministrations of her maid. She had not even troubled to tell her father, although the elderly peer was her only near relative. Not until he was seated at breakfast did she inform him in level, passionless tones of what had happened. Even then she said nothing of her suspicions of Ralph Fairfield. But for her pale face she might have been speaking of something in which she was but slightly interested.

The Duke of Burghley dropped his knife and fork at her first words. As she finished, he stood over her and passed a hand tenderly around her.

"My poor, poor little girl," he said. "This is terrible. Fairfield ought to have seen me first. I must telephone for your aunt to come and stay here until we can get away."

She shook her head a trifle impatiently.

"I don't want her, father. She cannot help me. I would rather be here alone with you. It would drive me mad to have sympathy showered on me. I want to see no one. I want to be left to myself."

"But—my dear, I know it is a shock, but you cannot be allowed to brood——"

She rose abruptly from the table and put him from her.

"I shall not brood," she said. "I shall work. I am going to Scotland Yard to learn what they know."

"Yes, yes, if you wish it," he said soothingly. "We will go at once. I will order the car now."

"I would rather go alone, if you don't mind," she said decisively, and the door closed behind her.

"She always was headstrong," remarked the Duke of Burghley to the devilled kidneys, and stared moodily into the fire.

Since his wife had died he had always been governed by his impetuous, strong-willed daughter, and accepted the situation philosophically so long as he had his books and his club. He led a complacent life from which he was rarely stirred. But he was hit harder than he cared to admit by the way in which she accepted the tragedy. He wondered vaguely what he ought to do, and decided to consult Brown—Brown being the senior member of his firm of family solicitors.

In his room at Scotland Yard Superintendent Heldon Foyle, a cigar between his teeth, was studying the book which his staff was compiling. Already it formed a bulky volume of many hundred typewritten pages. Here were reports, signed statements, photographs, personal descriptions, facsimiles of finger-prints, telegrams, letters, surveyors' plans, notes—everything, important and unimportant, that might have a possible bearing on the case. The superintendent turned over the pages with a moistened forefinger, and made a note now and again on a writing-pad by his side.

"Puzzling cases are like a jig-saw puzzle," he had once said. "You juggle about with the facts until you find two or three that fit together. They give you the key, and you build the rest up round 'em. But it's no good trying to do it unless you've got your box of pieces complete."

His box of pieces was not complete, and he knew it. Nevertheless, he could not resist trying to fit them together. But the announcement made by his clerk of the arrival of Lady Eileen Meredith came while he was still puzzling. She stood in the doorway, a dainty figure in furs, a heavy veil drawn over her face.

"Mr. Foyle?" she asked hesitatingly.

He bowed and wheeled a big arm-chair near his desk.

"Yes. Won't you sit down, Lady Eileen? You have just missed one of our men. I sent him round to break the news to you. I need not tell you that we recognise how you must feel in these terrible circumstances. We shall trouble you as little as possible after you have answered a few questions."

He was studying her shrewdly while he spoke, and her strange composure struck him at once. Even to her he had decided to say nothing of the identity of the murdered man. That could wait until he had had a better opportunity to judge her.

She sat down and rested her chin on one slim, gloved hand, her elbow on the desk.

"That's very good of you," she said formally. And then broke direct into her mission. "Have you found out anything, Mr. Foyle?"

"It's rather early to say anything yet," he hedged. "Our inquiries are not completed."

"There is no need for further inquiry. I can tell you who the murderer is."

Superintendent Foyle coughed and idly shifted a piece of paper over the notes on his blotting-pad. His face was inscrutable. She could not tell whether her statement had startled him or not. For all the change in his expression she might have merely remarked that the weather was fine. Had it been any one else he would have said that before the day was out he expected a dozen or more people to tell him that they knew the murderer—and that in each case the selection would be different. As it was he merely said with polite interest—

"Ah, that will save us a great deal of trouble. Who is it?"

"He is—I believe him to be Sir Ralph Fairfield."

The superintendent's eyelids flickered curiously; otherwise he gave no sign of the quickening of his interest. He was a judge of men, and although Fairfield had rebuffed him he did not believe him to be a murderer. Still, one never knew. Those who kill are not cast in one mould. If Sir Ralph had slain Goldenburg in mistake for Grell, and Lady Eileen knew there must be a motive—for that motive he had to look no further than the beautiful, unsmiling face before him.

"You realise that you are making a very grave accusation, Lady Eileen?" he said. "What reason should there be?"

She spoke rapidly, steadily, and he did not interrupt her. His pen rushed swiftly across the paper, taking down her words. They would presently be neatly typed and added to the book. When she paused, he replaced the pen tidily in its rack.

"This is what it comes to—that at eleven o'clock Sir Ralph said Mr. Grell was with him. You say that you had refused an offer of marriage from Sir Ralph, and think that he murdered Mr. Grell from jealousy. I may say that, though we know Sir Ralph was at his club for dinner and at eleven o'clock, we can find neither servants nor members who can say for certain that he was there at the time the murder was committed."

She caught her breath. "Then it was he!" she exclaimed eagerly. "Bob had not another enemy in the world. You will arrest him."

"Not yet," Foyle retorted, and noted that her face fell. "All this is only suspicion. We must have proof to satisfy a jury before we can do anything with a man in Sir Ralph's position. And now, if you don't mind, I should like to put a few other questions to you."

When she left after half an hour, Foyle threw back his head with a jerk.

"A pleasant girl," he commented. "Seems wonderfully anxious to have Fairfield hanged. I suppose she was really infatuated with Grell. You never know how women are going to take things. I wonder if I can get a set of his finger-prints. That ought to settle the matter one way or the other, so far as he is concerned. But it won't clear up what Goldenburg was doing in Grell's place. I'll have to fix that somehow."