It would have been very easy, with no obstacle worth mentioning to interpose. No one who saw them would have thought it particularly strange to see the nurse and the doctor leaving together. At most, it would have suggested that they were on unusually good terms, and that he was taking her out for an airing in his car. The keen-witted physician had progressed thus far by the time Nick arrived, but he had not yet sought to verify his deductions by questioning any of the hotel staff. Nick listened to his theory, put a few additional questions to the nurse, and then complimented Doctor Lightfoot on his analysis. “That seems to be the way of it,” the detective admitted. “A light, three-quarter-length coat, which the nurse often wore over her uniform, is also missing, together with her hat. The distinctive nurse’s skirt would have shown beneath the coat and thereby help the deception.” Confidential inquiries were made at once, and the fact was established that the two masqueraders--one voluntary and one involuntary--had left the building about ten o’clock the night before. The supposed Lightfoot had arrived in a smart, closed town car, which had been near enough to the physician’s in appearance to deceive the carriage starter. The chauffeur wore a quiet livery, a copy of that worn by Lightfoot’s driver. The car had waited, and the two had ridden away in it. That was all the hotel people could say. The night clerk had thought it odd that Miss Lund’s nurse had not returned, but it was none of his business, of course, if the actress’ physician had taken her away. It was of little importance now, but Nick was curious enough to make inquiries, while he was about it, which brought out the fact that a man had registered at the hotel the morning after the affair at the theater, and had paid his bill and left the evening before. It might have been only a coincidence, but certain features of the man’s description, as given, left room for the belief that Doctor Grantley had really been at the Wentworth-Belding during that interval. But where was he now, and what had he done with the unfortunate actress? Such as it was, the slender clew furnished by the closed car must be followed up for all it was worth. That was not likely to prove an easy matter, and, unless Grantley had lost his cunning, the trail of the machine would probably lead to nothing, even if it could be followed. Nevertheless, there seemed to be nothing else to work on. The chauffeur of the car might have been an accomplice, but it was not necessary to suppose so. It looked as if the wily Grantley had hunted up a machine of the same make as Doctor Lightfoot’s, and had engaged it for a week or a month, paying for it in advance. There are many cars to be had in New York on such terms, and they are extensively used by people who wish to give the impression, for a limited time, that they own a fine car.