"Of course, our conjurer knows where the stone is. It is in the custody of an old man who has a young wife. The old man with the young wife has countless gems for safe custody. From time to time he lends these gems to his wife to wear, though, with the characteristic caution of his tribe, he never says anything to the owners. Well, here is the conjurer's card forced from him, so to speak. All he has to do now is to design an occasion when the transfer may be made. We will say it is to be at a brilliant party—a fancy-dress ball, where gems may play a leading part. The victim will be there. As the Blue Stone of Ghan is a ruby, he naturally suggests rubies, much as the common conjurer with his magic bottle induces his assistant on the stage to choose the kind of liquid he wants to dispense. Says he to himself, that old man will offer his young wife the Blue Stone as a kind of crown of glory, and she will take it, not knowing what it is. Once she arrives at the fancy-dress ball the rest is easy. Do I interest you so far?"
"Wonderfully," Frobisher croaked. "Fancy finding the conjurer out like that. But though you have spoiled the trick, he must have the forced card, in this case represented by the—but why complete the phrase?"
"Why, indeed?" Isa Benstein asked serenely. "The brilliant trick as a brilliant trick has failed, for the simple reason that the involuntary medium has been too clever for her part. But I see that the conjurer is not so disconcerted as he might be, because he can always fall back upon his bully method whereby he sometimes disguises failure and leads up to a success in a fresh line. Is it to be the bullying policy, Sir Clement?"
Sir Clement bent forward and nodded eagerly. His yellow teeth were all exposed in a wide grin. Lefroy sat regarding him with open contempt. A clock somewhere struck two; the strains of the band floated in.
"I should like to borrow the Blue Stone," Frobisher said hoarsely.
"We will discuss that presently," Isa Benstein went on. "Perhaps I had better finish my train of logical reasoning. There was danger of the trick failing, in so much as the Blue Stone might have been recognised. And here was a further resource open to the conjurer. It was open to him to put aside the tricks of his trade and take the stone, take it with violence, if necessary. He would argue that his victim dared not speak, that she would put up with the loss rather than tell a story that nobody would believe. The idea of a man robbing his guest with violence under his own roof—and such a roof!—would be scouted by any common-sense person. Again, the unconscious medium would have her husband to consider. If the true facts of the case came out he would be ruined; there would be a scandal that might end in a gaol. Of course, when the desired mischief had been worked, the stone would be restored again, discreetly found before it was lost. Really, gentlemen, my imagination makes me nervous. As I sit opposite you, I am inwardly alarmed lest you should fall upon me and despoil me of a thing I would not have touched had I been aware of the true history of the case. I know I am foolish——"
"Madame," said Frobisher, rising with a bow. "You cruelly malign yourself. I have had some experience of clever people, and you are by far the cleverest woman I have ever met. Your insight is amazing, of your courage there can be no doubt. But don't carry your courage too far."
Mrs. Benstein had risen in her turn, the critical moment had come, but she gave no sign. Frobisher stood also, shaking his head doggedly.
"You deem discretion to be the better part of valour," the woman said. "The English profess never to know when they are beaten! Surely that is carrying the thing too far. The man who knows when he is beaten is the most valorous foe, for the god of war is always on the side of heavy battalions. You want the stone?"
"I must have it," said Frobisher.