"There is nothing supernatural about the matter, madam," Duvall remarked. "I don't doubt the explanation is simple enough, could we but hit upon it. But so far I confess I am unable to understand it." He went over to the wall which adjoined that of the house next door, and sounded it, inch by inch, with a small hammer he took from his bag of tools. The operation required several minutes. When he had completed it, he tossed the hammer back into his kit in disgust. "Brick, of course," he said, "and perfectly solid." He turned toward the door. "What are you going to do now?" Mrs. Morton asked. "Try to find out something through this telegram. And also, investigate the house next door." "But, you will come back? I am afraid." "I shall be at your call at all times, Mrs. Morton. If anything of interest occurs, notify me here." He drew a card from his pocket and wrote upon it the name of his hotel. "Say nothing to your daughter about these new threats. I shall probably see you again later in the day." Shouldering his kit of tools, Duvall left the apartment. He was by no means satisfied with the results of his visit. In fact there had apparently been no results at all. CHAPTER V Duvall's first move, after leaving Mrs. Morton's apartment that morning, was to enter the taxicab which had been waiting for him at the door and return to his hotel. A light overcoat which he had in the vehicle concealed his workman's disguise sufficiently to enable him to reach his room without exciting comment. Once there, he changed his clothes, putting on a professional looking frock coat, and adjusting a pair of shell-rimmed eyeglasses to complete the slight disguise. Thus equipped, he once more set out. Grace had left a note for him, saying that she had gone shopping. Beside it lay the photograph of Ruth Morton, which he had, he remembered, left on his chiffonier while putting on his workman's clothes that morning. At the foot of her hastily written note Grace had added a postscript. "Is _this_ the reason for your sudden interest in motion pictures?" it read. "Well, I'll admit she's a raving beauty, Richard, but I'll bet she isn't half as nice as I am." Duvall read the note with a smile. Grace was always such a thoroughly good comrade. Leaving the hotel, he went to the telegraph office from which the message to Ruth Morton had been delivered that morning. It was on Columbus Avenue, some four blocks from the Mortons' apartment. "Can you tell me where this telegram was sent from?" he asked. The message showed that it had been filed, as well as delivered, within the city limits. The man behind the desk looked up his records. "It was sent from the main office on lower Broadway, at 8.30," he said, briefly.