Leaving Mrs. Morton with a few words of encouragement, he made his way to his hotel. There was no news there of Grace, however, and he realized that it was now too late to accomplish anything by returning to the house on 57th Street. Marcia Ford would either have long since retired, or else would have left the house to communicate with the woman who had been with her earlier in the evening. Considerably upset by the events of the past three hours, Duvall retired to his room, and sat down to think the whole matter over. Proceeding on the assumption that the woman in question, and Miss Ford were acting together, all the events at the studio, the fake telegram, the missing photograph, became intelligible. But the delivery of the letters in Ruth Morton's apartment, the strange attack upon him while searching the Ford girl's room, were by no means so clear. Once more his thoughts reverted to the attic room, the roof of the adjoining house, the problem of effecting an entrance to the Morton apartment through either of the two windows. And then, as he revolved the problem in his mind, a sudden light came to him. He sprang from his chair with an exclamation of satisfaction. A solution of the whole matter flashed through his brain, a solution at once so simple, and so ingenious, that he wondered he had not thought of it before. He glanced at his watch. It was midnight. Too late, perhaps, to test the accuracy of his deductions. Nor did he feel at all easy in his mind regarding Grace. Something must have happened to her, he feared, to keep her out so late, with no word to him concerning her movements. He went to the 'phone, and calling up the office, inquired whether anything had been heard of Mrs. Duvall. "No," the night clerk informed him. Mrs. Duvall had not been heard from, nor had she sent any message. But a note had just been left for her. He would send it up. Duvall awaited the arrival of the note with the utmost impatience. A message for Grace. From whom? What could it mean? A few moments later one of the bellboys thrust into his hand a letter, written on the note paper of the hotel. He regarded the scrawling and ill-written superscription with apprehension, then tore open the envelope and proceeded to read the contents of the note. "Dear Madam," it said. "I waited till nearly midnight. When you did not come, I thought you must have gone out some other way, so came back to the hotel. I hope I did right. Respectfully yours, Martin Leary." Duvall stared at the words before him with a look of alarm. Who was Martin Leary? And where had he waited for Grace until nearly midnight? And, above all, why had she not returned? Had some accident, some danger befallen her? The circumstances made it seem highly probable. There was but one thing to do--to question the night clerk, and find out, if possible, who Leary was. He rushed to the elevator and made his way to the lobby with all speed. "Who left this note for Mrs. Duvall?" he asked of the clerk.