"This picture was made by Gibson, on Fifth Avenue," she said, referring to the photograph in the book. Both Baker and Duvall saw at once that on the retouched picture, the name of the photographer had been scratched off. "How many of them were made, and what became of them?" Duvall asked quickly. "Ordinarily I could not answer such a question," Mrs. Morton replied, "for Ruth has had many photographs taken, and we have not of course kept a record of them, or what has become of them, but in this particular case I happen to remember that she did not like the pose particularly, and ordered but half a dozen. I do not think that she gave any of them away. If I am right in my supposition, there should be five more here in the apartment." Closing the book, Mrs. Morton went to the cabinet again, and took out a portfolio containing numberless photographs of her daughter in all sorts of poses. After some searching, she produced a brown-paper envelope, containing a number of pictures, all taken by the same photographer, at the same time. There were in the envelope four copies of the photograph, the fifth of which was contained in the album. "Evidently one has been given away," Duvall exclaimed. "Now if we can only find out to whom, our search for the writer of these letters may be very quickly ended." Mr. Baker regarded them both with a puzzled look. "I have seen that picture before," he said, "and of course I could not have done so, had I not seen the one that is missing." He sat for a while in silence, searching his recollection for a solution of the problem. Suddenly he spoke. "There was a picture like that in my office, at one time," he exclaimed. "Miss Morton sent a number down, for advertising purposes, and I am positive that this one was among them. I remember distinctly the pose of the head, the unusual arrangement of the hair. That photograph should be in our files. The fact that it has been taken out shows that the person who has been writing these letters is a member of our own staff, or at least has access to our files." "That does not necessarily follow," observed Duvall. "Why not?" "Because the picture might have been obtained from the photographer." "But they are not allowed to dispose of the portraits of others, without the sitter's permission." "I know that, but they sometimes do so, especially in the case of anyone so well known as Miss Morton. She has become a sort of public character. "Well," remarked Duvall, "we can readily find out, in the morning. You, Mr. Baker, can go through your files, and should you find the photograph to be there, I will take the matter up with the photographer. If, on the contrary, the picture is missing, it will be fairly conclusive evidence that the person or persons we are looking for are in some way connected with the studio." "I will make an investigation the first thing in the morning," Mr. Baker announced, rising. "Do you expect to be at the studio early, Mr. Duvall?" "Yes. Quite early."