It was a long and tedious search. Most men would have given up in the first few minutes, or at the end of an hour, but not so Green-eye Gordon. There was an ugly expression on his face, and his nerves were on edge, but he kept on with a dogged determination, scrutinizing the enameled surface of the safe inch by inch, and going over it not once, but many times. The fact that the safe was set into the wall gave him a comparatively small surface to cover, and seemed to promise success without any great effort, but the promise was without foundation. Nevertheless, the scoundrel’s persistence was finally rewarded. He located the secret spring, but did so purely by accident, not from any help which his keen eyes, or Nick’s powerful magnifying glass gave him. The reason was that the spring was located in a comparatively inaccessible place, behind one of the legs of the safe. Gordon had lain down again and again, and, with the help of a pocket flash light and the magnifying glass, had done his best to peer under the low safe and behind the two squat little legs at the front. He had met with very little success, but finally, having failed to find what he sought elsewhere, he had begun feeling about at random. In this way, just behind the right leg, and in the bottom of the safe, he had happened upon a small, yielding surface, and his heart had bounded as he pressed it upward. To his delight, the inner door began to open noiselessly. Simultaneously, the impostor’s heart stopped. Some one had knocked at the door! CHAPTER XX. THE BLACKMAILER’S SUPREME HAUL. For a moment that seemed an eternity, Ernest Gordon crouched as if petrified, his eyes turned wildly to the door. Had he locked it? Of course he had, but he could not be sure of it at that moment, and, even if it were locked, what beastly mischance had brought an interruption just then? Supposing it were Carter himself, or one of his assistants? The rascal’s clammy hands were cold, and his knees threatened to collapse under him. Gritting his teeth, however, and with a look of contempt for his own weakness, he pushed the inner door back, swung the other one around until it was only slightly ajar, and, after a hasty glance about to make sure that all else was in order, strode to the door. “What is it?” he called harshly. Even at the moment of utterance he was conscious that the voice bore little resemblance to that of the man he was impersonating. The reply, to his relief, was in the butler’s deferential tones. “Telegram, sir,” Joseph announced. “I’m sorry to disturb you, but I thought you probably would like to have it at once.” “That’s all right,” Gordon said, taking care this time to imitate Nick’s voice accurately. He unlocked the door and opened it a foot or so. “Thanks, Joseph,” he said, taking the telegram from the butler’s silver salver, and closing the door again, but not locking it.