He paused, then went on. "Someone thought out this plan of using narcophin and scopolamine to cause the twilight sleep, to keep Rawaruska just on the borderland of unconsciousness, destroying her memory and producing forgetfulness. That is the dämmerschlaf; perception is retained but memory lost. You are acquainted with the test? They show an object to a patient and ask her if she sees it. Say, half an hour later, it is shown again. If she remembers it, it is a sign that a new injection is necessary.

"Only in this case the criminal went too far, disregarded the danger of the thing. Scopolamine in too great a quantity causes death by paralysis of respiration—a paralysis, by the way, against which artificial respiration and all means of stimulating are ineffective because of the rigidity of the muscles. And so, you see, in this case Rawaruska died."

I could not help thinking of Preston, the young doctor who had been studying in Germany. More than likely he had heard of and had investigated the Frieberg "twilight sleep" treatment. We had made some progress, even though we did not know why or by whom the drugs had been administered.

Wade, of the Customs Service, had, as I have said, told us that he had several secret agents about in the trade, constantly picking up bits of information that might interest the Treasury Department. It did not surprise Kennedy, therefore, late in the forenoon, to have Wade call up and tell him that among the early callers at Margot's, the jeweler, was the maid Cecilie.

"That was where she must have been before I reached the Vanderveer," I exclaimed.

Kennedy nodded. "But why did she go there?" he asked. "And why was she talking with Preston?"

Inasmuch as I couldn't answer the questions I didn't try, but waited while Craig reasoned out some method of attack on them.

"Since it's known that we're working on the case of Rawaruska," he ruminated half an hour later over an untasted lunch, "we might just as well take the risk of seeing Margot himself. Let's go down and look his shop over."

So in the middle of the afternoon, when Fifth Avenue was crowded with shoppers, we paused before Margot's window, looking over the entrancing display of precious stones gleaming out from the rich black velvet background, and then sauntered in, like any other customers.

Kennedy engaged the salesman in talk about necklaces and lavallieres, always leading the conversation around to the largest stones that he saw, and dwelling particularly on those that were colored. As I listened, trying to throw in a word now and then that would not sound absolutely foolish, I was impressed by a feeling that Margot's, even though it was such a fashionable place, was what might be called only a high-class shyster's. In fact, I recalled having heard that Margot had engineered several rather questionable transactions in gems.