Mrs. May, Princess Zara, the brilliant mystery who wielded so great an influence over the destiny of the house of Ravenspur, lay on her bed smiling faintly in the face of Mrs. Gordon Ravenspur, who stood regarding her with friendly solicitude. Mrs. Gordon had no suspicions whatever; she would have trusted any one. All the lessons of all the years had taught her no prudence in that direction. A kind word or an appeal for assistance always disarmed Mrs. Gordon.

"I hope you are comfortable?" she asked.

Mrs. May smiled faintly. She appeared a trifle embarrassed. She was acting her part beautifully as usual. Her audacity and assurance had carried her through great difficulties and she had confidence in the future.

"In my body, perfectly," she said. "But I am so uneasy in my mind."

"And you will not have a doctor?"

"Not for worlds. There is nothing the matter with me. I have suffered like this before. I have a weak heart, you know, and excitement troubles me thus. But I don't want a doctor."

"Then why should you worry?" Mrs. Gordon asked.

"I am ashamed of myself," the woman confessed with a laugh. "I have been wondering what you must think about me. This is the second time you have had to detain me as an involuntary guest under your roof. The first time I was the victim of idle curiosity; the second time I did try to do you a good turn. I hope you will remember that."

"It was kind and courageous of you," Mrs. Gordon said warmly. "How many people would have done as much for strangers! And please do not talk about it any more or I shall be distressed."

Mrs. May was by no means sorry to change the conversation. A thousand questions trembled on her lips, but she restrained them. She was burning to know certain things, but the mere mention of such matters might have aroused suspicions in a far simpler mind than that of Mrs. Gordon.

"So long as you are all well it doesn't matter," she said. "This afternoon I shall make an effort to get up. Meanwhile, I won't keep you from your household duties. Could I see one of those charming girls, Miss Vera or Marion? I have taken such a fancy to them."

"Vera shall come presently; she has gone to the village," Mrs. Gordon explained. As to Marion she could say nothing.

"Marion has been an enigma to us lately," she explained. "I need not tell you of the dark shadows hanging over this unhappy house, or how near we have been to the solution of the mystery on more than one occasion. And now Marion has an idea, queer child.

"She went out, presumably last night, leaving a note to say she had really got on the track at last, and that we were not to worry about her even if she did not return to-day. So strange of Marion."

Mrs. May had turned her face away. She was fearful lest the other, prattling on in her innocent way, should see the rage and terror and despair of her features.

"Queer!" she murmured hoarsely. "Did she write to you?"

"No, to my husband's father. Her note was given to me. Even now I don't know what to make of it. Would you like to see the letter? You are so clever that you may understand it better than I do."

"I should like to see the letter."

It was an effort almost beyond the speaker's powers to keep her voice steady. Even then the words sounded in her ears as if they came from somebody else. From her pocket Mrs. Gordon produced the letter. Mrs. May appeared to regard it languidly.

"If I knew the girl better I could tell you," she said. "It sounds sincere. But my head is beginning to ache again."

Mrs. Gordon was all solicitude. She drew down the blinds, and produced eau de Cologne, and fanned the brow of the sufferer after drenching it with the spirit. Mrs. May smiled languidly but gratefully. At the same time it was all she could do to keep her hands from clutching the other by the throat and screaming out that unless she was left alone murder would be done.

"Now I really can leave you," Mrs. Gordon said.

"It would be the greatest kindness," the invalid murmured gratefully.

The door softly closed; Mrs. May struggled to a sitting position. Her eyes were gleaming, yet a hard despair was on her face. She ought to be up and doing, but her lower limbs refused their office.

"A forgery," she said between her teeth. "Marion never wrote that letter. If they were not blind they could see that for themselves. Marion has been decoyed away; and, if so, somebody has that key. If I only knew. Tchigorsky is dead and Ralph Ravenspur is an idiot. Who, then, is the prime mover in this business?"

The woman did not know, and for the life of her she could not guess. Tchigorsky was out of the way—dead and buried. Ralph Ravenspur and Geoffrey were antagonists not worthy of a second thought. But somebody was moving and that somebody a skilled and vigorous foe.

For once the arch-conspirator was baffled. The foe had the enormous knowledge of knowing his quarry, while the quarry had not the least notion where or how to look for the hunter. And the fish was fast to the line. Unless it got away at once the landing net would be applied; then there would be an end of all things.

But she could not move; she could do nothing but lie there gasping in impotent rage. There was only one person in the world who could help her now, and that was Marion. And where was Marion? Only the man on the other side of the chess board knew that.

She wished she knew; oh! she wished she knew a score of things. Did the people of the castle suspect her? Hardly that, or Mrs. Gordon had not been so friendly.

What had become of the coat and glass mask she was wearing at the time things went wrong in Geoffrey Ravenspur's room? Had her subordinates heard her cry? Had they fled, or had they been taken? If they had fled, had they removed the instruments with them?

Mrs. May would have given five years of her life for enlightenment on these vital questions. Even she could not read the past and solve the unseen.

Tears of impotent rage and fury rose to her eyes. While she was lying there wasting the diamond minutes the foe was at work. At any time that foe might come down with the most overwhelming proofs and crush her. Marion had been spirited away. Why? So that the key of the safe might be stolen and used to advantage.

Once more the woman tried to raise herself from the bed. It was useless. She slipped the bed-clothes into her mouth to stifle the cries that rose to her lips. She was huddled under them when the door opened and Vera stepped in.

"Did you call out?" she asked. "I was passing your door and fancied I heard a cry. Are you still suffering from a headache?"

Mrs. May's first impulse was to order the girl away. Then an idea came to her.

"The headache is gone," she said sweetly. "It was just a twinge of neuralgia. I wonder if you would do me a favor."

"Certainly."

"Then I wish you would get me some paper and envelopes. I have a note to write. There is a child in the village I am fond of. She comes and sits in the tangle at the bottom of the Jessops' garden and talks to me. I am afraid she thinks more of my chocolates than me, but that is a detail."

"You want to write the child a note. How sweet of you!"

"Oh, no," Mrs. May said. She was going to embark on a dangerous effort and was not quite certain as yet. But desperate diseases require desperate remedies. "It is nothing. And I don't want anybody to know."

"I am sure you can trust to me."

"Of course I can, my dear child. And I will. Please get me the materials."

Vera brought the paper and essentials. With a smile on her face Mrs. May wrote the letter. Inside the envelope she placed something she had taken from the bosom of her dress.

"A cake of chocolate," she explained smilingly. "See, I do not address the envelope, but place on it this funny sign that looks like an intoxicated problem in Euclid. The child will understand. And now I am going to ask you to do me a favor. Will you please take the letter without letting anybody know what you are doing, and put it at the foot of the big elder in the tangle? I dare say it sounds very stupid of me, but I don't want the child to be disappointed."

Vera professed herself ready and also to be charmed with the idea. She would go at once, she said, and Mrs. May raised no obstacle. At the end of the corridor Vera was confronted with her uncle Ralph. He held out his hand.

"I was listening," he said. "I knew beyond all doubt that something of the kind would be attempted. I want that letter."

"But uncle, I promised——"

"It matters nothing what you promised. It is of vital importance that the inside of that letter should be seen. Chocolate for a child, indeed. Death to us all, rather. You are going to give me that letter and I am going to open it. Afterwards it shall be sealed again, and you shall convey it to its destination. The letter!"

Dazed and bewildered, Vera handed it to him. It was not a nice thing to do, but, then, nice methods were not for Mrs. May. Ralph grasped the letter and made off towards his room.

"Wait here," he said. "I shall not be a few minutes. I am merely going to steam that envelope open and master the contents. Don't go away."

Vera nodded. She was too astonished for words; not that she felt compunction any longer. Presently Ralph returned.

"There you are, my child," he said. "If I seemed harsh to you, forgive me. It is no time for courtesies. You can take the letter now and deliver it. It has been a good and great discovery for us."