"I had them bring him to headquarters at once, and we hadn't sweated him fifteen minutes before he confessed that he'd seen the chance to cover his embezzlement by blaming a theft on the Invisible Master. I didn't know what to think. Could it be that the other crimes were the same in nature? I had them round up Taylor and Allen at once. Taylor was found on the point of sailing for Europe, having resigned his position on the ostensible account of shattered nerves. He proved a harder case than Harkness, but an hour of grilling brought from him the admission that he too had blamed his theft of the money and killing of Barsoff on the Invisible Master, and had only planned the crime because he saw a chance to do it thus free of all suspicion. I don't think he'd ever have come clean if we hadn't found most of the money involved there in his grips. "Allen, though, went to pieces at our first question and confessed volubly that his crazy hatred of his three partners had made him plan a killing of them that all would think the Invisible Master's work. The funny thing, was, too, that each one of the three believed that the other two crimes had been really the Invisible Master's work! "I was amazed, stupefied. If the Invisible Master had not committed those crimes, then his demand for the five millions was simply a gigantic bluff. Was there, then, any Invisible Master at all? Was there, the thought flashed over me for the first time, any such power of invisibility as Grantham claimed to have discovered? I boiled it all down and found that the only real evidence of the invisibility part of it was the demonstration Grantham had given. I grabbed all the books on optics I could find in an effort to learn whether such a demonstration could be faked, and soon found out about the tourmaline crystals and their remarkable property. It all fitted in exactly with the demonstration as it had been described to me. Grantham had made no demonstrations at all since that first one, nor had we dreamed of asking him for them, so utter was our belief in his word and in the Invisible Master's existence. "I made some swift inquiries and the whole thing burst clear on me. There had never been any invisibility or any Invisible Master at all. Grantham had planned the great bluff that was to wring five millions out of the city, had built it up from the trick of that first demonstration and from the circumstantial evidence he was able to gather to support the thing, had used the crimes that inevitably resulted from the city's belief in the Invisible Master to make that belief even stronger. I drove out to the place where we were last night and it took but minutes of searching to find the concealed niche beside the stone where the money still lay.