That was all. She crossed the room and passed out of it, not through the window which was quite convenient, but through the solid wall. I sat there for a full minute, staring at the spot where I had last seen her and endeavoring to convince myself that I was dreaming, but I was not dreaming; I was wide awake. In fact I was so wide awake that it was fully an hour before I had successfully wooed Morpheus, as the Victorian writers so neatly expressed it, ignoring the fact that his sex must have made it rather embarrassing for gentlemen writers. I reached my office a little earlier than usual the following morning, and it is needless to say that the first thing that I did was to search for that letter which I had received on the tenth. I could recall neither the name of the writer nor the point of origin of the letter, but my secretary recalled the latter, the letter having been sufficiently out of the ordinary to attract his attention. “It was from somewhere in Mexico,” he said, and as letters of this nature are filed by states and countries, there was now no difficulty in locating it. You may rest assured that this time I read the letter carefully. It was dated the third and postmarked Guaymas. Guaymas is a seaport in Sonora, on the Gulf of California. Here is the letter: My dear Sir: Being engaged in a venture of great scientific importance, I find it necessary to solicit the assistance (not financial) of some one psychologically harmonious, who is at the same time of sufficient intelligence and culture to appreciate the vast possibilities of my project. Why I have addressed you I shall be glad to explain in the happy event that a personal interview seems desirable. This can only be ascertained by a test which I shall now explain. If a female figure in a white shroud enters your bedchamber at midnight on the thirteenth day of this month, answer this letter; otherwise, do not. If she speaks to you, please remember her words and repeat them to me when you write. Assuring you of my appreciation of your earnest consideration of this letter, which I realize is rather unusual, and begging that you hold its contents in strictest confidence until future events shall have warranted its publication, I am, Sir, Very respectfully yours, CARSON NAPIER. “It looks to me like another nut,” commented Rothmund. “So it did to me on the tenth,” I agreed; “but today is the fourteenth, and now it looks like another story.” “What has the fourteenth got to do with it?” he demanded. “Yesterday was the thirteenth,” I reminded him. “You don’t mean to tell me—” he started, skeptically. “That is just what I do mean to tell you,” I interrupted. “The lady came, I saw, she conquered.” Ralph looked worried. “Don’t forget what your nurse told you after your last operation,” he reminded me.