Was this girl a plotter, too? If he could have seen that note! And then the organ-grinder--. On the whole, he was not even half satisfied with the result of his expedition, especially when he remembered that organ-grinder, and how he had let his temper escape its leash and rage itself into that cold white heat, his most intense expression of wrath, in which he had openly defied Alan Warburton, and flung his own colors boldly forth. Another thing puzzled Vernet exceedingly. He had discovered Richard Stanhope at the Warburton masquerade, and had bestowed upon him the character of lover. Was he there in that character? Was he, in any way, mixed up with their family secrets? Where had he spent the remainder of that eventful night? Since the morning when Stanhope had reported to his Chief, after his night of adventure beginning with the masquerade, Vernet had heard no word from that Chief concerning Stanhope's unaccountable conduct, or the abandoned Raid. The whole affair was to Vernet, vague, unsatisfactory, mysterious. But the more unsatisfactory, the more mysterious it became, the more doggedly determined became he. He had not forgotten, nor was he neglecting, the Arthur Pearson murder. He was pursuing that investigation after a manner quite satisfactory--to himself at least. There are in most cities, and connected with many detective forces, and more individual members of forces, a class of men, mongrels, we might say,--a cross between the lawyer and the detective but actually neither, and sometimes fitted for both. They are called, by those initiated, "private enquirers," "trackers," "bloodhounds." These gentry are often employed by lawyers, as well as by detectives and the police. They trace out titles, run down witnesses, hunt up pedigrees, unearth long-forgotten family secrets. They are searchers of records, burrowers into the past. Their work is slow, laborious, pains-taking, tedious. But it is not dangerous; the unsafe tracks are left to the detective proper. Into the careful hands of some of these gentry, Van Vernet had entrusted certain threads from the woof of the "Arthur Pearson murder case," as they styled it. And these tireless searchers were burrowing away while Vernet was busying himself with other matters, waiting for the time when the "tracker" should find his occupation gone, and the detective's efforts be called in play. Vernet had not been aware of the close proximity of his sometime friend and present rival. He had felt sure, from the first, that the pretended mute was other than he seemed; that he was a spy and marplot. But Richard Stanhope's disguise was perfect, and Vernet had not scrutinized him closely, being in such haste to dispose of him, and expecting to investigate his case later. Then, too, Richard Stanhope was absent; he had not been seen, or heard of, at the Agency for many days.