last, at half-past six, at the general post office. How was the other letter delivered?"
"I do not know. I found it, yesterday forenoon, upon the floor in my daughter's bedroom, an hour or more after she had left the house. She has not seen it. I kept all news of it from her, as I did not wish her to be frightened."
"That was wise, of course," Duvall said. "But how could the letter possibly have been placed where you found it, without your knowledge? Who, beside yourself, was in the apartment at the time?"
"No one but an old negro cook, who has been with me for years. I am quite certain that she had nothing to do with it."
"And the maid of whom you speak?"
"She had left my daughter's room, and come into the dining room, where I was sitting, before Ruth left the bedroom. They went out together. The note could not have been in the bedroom then, or my daughter would certainly have seen it. The thing seems almost uncanny."
Duvall began to stroke his chin, a habit with him when he was more than usually perplexed. Presently he spoke.
"One thing I have learned, Mrs. Morton, after many years spent in detective work. There is no circumstance, however mystifying it may at first appear, which is not susceptible of some reasonable and often very commonplace explanation. You find this letter on the floor in your daughter's bedroom. It was placed there, either by someone within the apartment, or by someone from without. Now you tell me that it could not have been placed from within. Then I can only say that someone must have entered the room, or at least managed to place the letter in the room, from outside."
"That may be true, Mr. Duvall," remarked Mrs. Morton, quietly, "but when you consider that our apartment is on the fourth floor, that one of the windows of the room was closed, and the other only open a few inches, and that the blank wall of the opposite house is at least ten feet away, I fail to see how what you suggest is possible."
Her words filled Duvall with surprise. If what his caller said was true, the case might have elements which would make it more than usually interesting.
"Has your daughter any enemy, who might envy her her success, and wish to deprive her of it?" he asked.
"None, that I know of. But since these two letters came, I feel convinced that someone, whom, I cannot imagine, does feel that way toward her, and that on account of it she is in the gravest danger. Don't you think so, Mr. Duvall?"
"I think it highly probable. And what, Mrs. Morton, would you like to have me do in the matter?"
"Why – come to New York, take up the case, and find out who these wretches are, so that they may be prevented from doing my daughter any harm. There is no time to lose. They may carry out their threats at any moment. You will observe that in the first letter they said that her beauty would be destroyed 'within thirty days.' One of those days has already passed. To-day is the second. At most, we have but twenty-eight days left in which to find out who is responsible for this outrage. Investigation may consume a great deal of time. I hope that you will consent to come to New York and take charge of the matter at once. I am returning this afternoon, as soon as I can get a train. Can you not return with me? As for the matter of expense, I place no limit upon it. There is nothing I would not sacrifice, to save my daughter from the fate they have threatened. Think what it would mean, Mr. Duvall. A young, beautiful, innocent girl, scarcely more than a child, to go through life with her beauty taken from her, made hideous by some fiendish device, blinded and scarred by acid, her features crushed – gashed by some sudden blow. Can you imagine anything more terrible?"
Duvall thought for moment of his own lovely child, now almost three years old, and shuddered. Bank burglaries, thefts of jewels, seemed relatively of small importance compared with such a situation as this. His feelings of chivalry rose. He felt a strong desire to help this young girl.
"Here is her picture," Mrs. Morton continued, taking a photograph from her handbag and extending it to Duvall.
The latter gazed at the charming features of the young actress, and nodded.
"She is lovely – exquisite," he murmured. "I don't wonder you feel as you do. I did not intend to take up any detective work at this time, but I have decided to assist you in this matter in any way that I can."
"Oh – thank you, Mr. Duvall." There were tears in Mrs. Morton's anxious eyes. "I can never repay you for your kindness – never. But if you can save Ruth from these scoundrels, I will gladly spend – "
"Never mind about that, Mrs. Morton," Duvall observed, with a friendly smile. "It is scarcely a question of money with me. If I had not felt a keen interest in your daughter's welfare, I should not have agreed to take up the matter at all. As it is, you need not worry about the expense. I am going to take the case largely because it has interested me, and it will be a pleasure to work it out, not only on your daughter's account, but on my own. You know, to me, such matters are of absorbing interest, like the solving of some complex and baffling puzzle."
"Then you will go back to New York with me this evening?"
"I can hardly do that, Mrs. Morton. But I can agree to call on you there to-morrow. It will take me some hours to arrange matters here so that I can leave. I do not think you need worry for a few days at least. If these people had meant to act at once they would not have named the period of thirty days in their threats."
"Very well." Mrs. Morton rose, and held out her hand. "I will expect you to-morrow. Will it be in the morning?"
"Very likely. In any event, I will first telephone to you." He entered the address in his notebook. "By the way, perhaps you had better let me keep that photograph."
"Certainly." Mrs. Morton handed it to him, and he thrust it into his pocket. "The letters you already have?"
"Yes."
"Is there anything else?"
"Yes. One thing. Do not tell your daughter that you have employed me in this case. It – it might alarm her."
"Certainly not. And that leads me to say that you, on your part, will of course observe the utmost secrecy. Even with Mrs. Duvall."
"That goes without saying, madam. My professional secrets I share with no one. Even between my wife and myself there is an unwritten law which is never broken. Unless we are working on a case together – unless she can be of service to me, she asks no questions. She would not speak to me, or even recognize me, were we to meet, while I am engaged in work of this sort. You need have no fear on that score."
"I am very glad to know that. Were these people to suspect that I have placed the matter in the hands of a detective, they would be instantly on their guard, and all means of tracing them might be lost."
"That is undoubtedly true, and for that reason, I may appear in other characters than my own, from time to time, disguised perhaps, in such a way that even you would not recognize me. Under those circumstances I will suggest a password – one that will not be known to anyone else. Should occasion arise in which I desire to acquaint you with my identity, without making it known to others, I will merely repeat the words – twenty-eight days, or twenty-seven or six or five, as the case may be, on that particular day, and you will know that it is I, and act accordingly. Is that perfectly clear?"
"Perfectly, Mr. Duvall."
"Very well. Then we will leave further details until to-morrow." He shook hands with his caller, escorted her to her automobile, then returned to the library and began a careful study of the two notes which Mrs. Morton had left with him. Here Grace found him, half an hour later.
"Well,"
