Inspector Hanslet was rapidly becoming the foremost figure at Scotland Yard. He was a man who, without being brilliant, possessed more than the usual quickness of perception. He could, in his own phrase, see as far through a brick wall as most people, and to this attribute he added an agility of mind remarkable in a man whose training had been of a stereotyped kind. Early in his career he had become acquainted with Dr. Priestley, and the Professor, to whom a problem of any kind was as the breath of his body, had since encouraged him to come to Westbourne Terrace and discuss his difficulties. To many of these the Professor’s logical mind had suggested the solution. Since he refused to allow his name to be mentioned, the credit for his deductions descended upon Hanslet. As a matter of fact, the authorities knew very well how matters stood, and Hanslet was always employed upon those cases which promised to be complicated, since it was an open secret that he could call upon the advice and assistance of Dr. Priestley. It was evident that the sudden reaction of having nothing to do, after his unremitting labours of the past six months, was having an unfavourable effect upon Dr. Priestley’s temper. He roamed about the study, pulling out a file from time to time, and finding fault with Harold because some item did not come immediately to his hand. It was not until it was time to dress for dinner that he desisted from this irritating occupation. And even at dinner he was silent and morose, obviously seeking in vain for some new interest which should occupy his restless thoughts. But hardly had he and Harold finished their coffee, which they always had in the study after dinner, than Mary the parlourmaid opened the door softly. “Inspector Hanslet to see you, sir,” she announced. The Professor turned so abruptly in his chair as seriously to endanger the coffee cup he was holding. “Inspector Hanslet!” he exclaimed. “Why show him in, of course. Good evening, Inspector, it was only this morning that Harold and I were speaking of you. I hope that you enjoyed yourself in America.” “I did indeed, Professor,” replied Hanslet, shaking hands warmly with Dr. Priestley, and nodding cheerily to Harold. “Not that I’m not very glad to be home again; one’s own country’s best, after all. I landed at Southampton last Wednesday.” “And now you have come back to tell us of your experiences,” said the Professor. “I am sure we shall be most interested to hear them. Did you succeed in your object?” “Oh, yes, we rounded them up all right,” replied Hanslet. “My word, Professor, you ought to go over to New York and see the things the fellows do over there. As far as scientific detection goes, they’ve got us beat to a frazzle. You’d appreciate their methods. And they’re a cheery crowd, too. They gave me no end of a good time while I was over there.”