Nor was there evident any indication of the manner in which entry to the house had been gained, or the method by which the thieves had left. The windows and doors were unmarked. Not a bolt or lock had been forced. Throughout the night no suspicious noises had been heard, and it was only when in the course of ordinary routine that a maid had entered one of the exhibition rooms, at eleven o'clock in the morning, that the robbery had been discovered. "Not so much as a blighting finger-print," Bill Malone observed, and at the finish of a meticulous examination of the windows, added that it was the smoothest bust that he had ever run across in the course of his carmined career. But a mystery may be too mysterious, too faultily faultless. Any defect, any lapse on the part of the thieves might have left the police even more in the air. As it was, there remained little doubt in the minds of the detectives that their first surmise was right--that they could breathe in a word the name of the supreme culprit--but much doubt as to the possibility of acquiring evidence to run him down. The men who could plan or carry out such an undertaking were few. Malone put it into words. "This has got the hall-mark of Larry, guv'nor." Labar crinkled his brows, and nodded absently. The man who tackled this job would have in front of him a spasm of tough work, that in all probability would end in defeat by running his head against a brick wall. "Yes," he agreed. "It's got all that. Our friend Larry is certainly indicated, but we must not let ourselves be hypnotised about him. There's a bet you've overlooked, Bill." "An inside job." "It might be either--or both," said Labar, and turned with imperturbable face, that masked more than slight worry, to confront the shrewd beady eyes of Mr. Gertstein. "What do you think now?" demanded the millionaire. The inspector smoothed his chin. "I hate to make up my mind right away, Mr. Gertstein, but I'd be willing to make one guess at the man who knows all about this." "So!" Gertstein rubbed his hands. "Then you have found out something. You have a clue. I'm a generous man, Inspector. If you get back those things I will treat you well. It will be worth--what--a thousand pounds to you." "That's handsome of you, sir. But even if I was allowed to take a reward--which I couldn't do without the consent of the Yard--I wouldn't be too sure of getting it. As I say, I could give a guess about this business, but guesses don't carry us far. There isn't a shred of proof yet, and I tell you frankly I wouldn't gamble a half-penny on getting the men or getting the stuff." "But you--you're a detective." Gertstein tugged impatiently at his little beard. "If you know what you say it should be easy." "Easy, sir. Yes, it should be easy." Labar permitted a sardonic note to creep into his voice. "About as easy as taking treacle from a bear's mouth. I'm a detective, not a miracle worker."