"I, for one, agree with Sprague," said Doctor Thurston. "I am disappointed in the problem. I have seen Sturgis unravel some extremely puzzling tangles in my day; and such a case would not be hard to find. Why, no longer ago than this evening, on our way here, we stumbled upon a most peculiar case----eh?----oh!----er----please pass the cognac, Sprague. I wish I had some like it in my cellar; it is worth its weight in gold." Doctor Thurston had met Sturgis's steady gaze and had understood that, for some reason or other, the reporter did not wish him to relate their adventure of the afternoon. Only one person appeared to notice the abrupt termination of his story. This was Murdock, who had looked up at the speaker with mild curiosity, and who had also intercepted the reporter's warning glance at his friend. He observed Doctor Thurston narrowly for a full minute, appeared to enjoy his clumsy effort to cover his retreat, and then quietly sipped his coffee. CHAPTER IV. THE BANK PRESIDENT. Sprague's dinner party was over, and among the first to take their leave, shortly after midnight, were Dunlap, Sturgis and Doctor Thurston. The reporter did not often spend an evening in worldly dissipation. He was a man of action, a hard worker and an enthusiastic student. Almost all of the time which was not actually spent in the pursuit of his profession, was devoted to study in many widely different fields of art and science. For Sturgis's ideal of his profession was high; he held that almost every form of knowledge was essential to success in his line of work. It was seldom, therefore, that he allowed himself to spend a precious evening in social intercourse, unless as a more or less direct means to some end. He had made an exception in favor of Sprague's dinner, and his meeting with Dunlap, whom he had not previously known, had been entirely accidental. Dunlap was, however, a man whom Sturgis needed to see in the course of his study of the Knickerbocker bank mystery, and he had not lost the opportunity which chance had placed in his way. After obtaining an introduction to the bank president, the reporter had sought an occasion to speak with him in private; and, as this did not present itself during the course of the evening, he had timed his departure so that it should coincide with that of Dunlap. Doctor Thurston had followed his friend's lead. "Are you going down to the bank this evening, Mr. Dunlap?" asked Sturgis, as the trio faced the bleak wind. "I? No. Why should I?" inquired the banker in apparent surprise.