"And I think you are quite right," he cried heartily, to Mr. Ricardo's surprise. "Tell them the truth before they suspect it, and they will help you out of the affair if they can. Not a doubt of it. Come, I will go with you myself to Scotland Yard." "Thank you," said Joan, and the pair drove away in a cab together. Hanaud returned to Grosvenor Square alone and lunched with Ricardo. "It was all right," he said. "The police were very kind. Miss Joan Carew told her story to them as she had told it to us. Fortunately, the envelope with the aluminium chain had already been delivered, and was in their hands. They were much mystified about it, but Miss Joan's story gave them a reasonable explanation. I think they are inclined to believe her; and, if she is speaking the truth, they will keep her out of the witness-box if they can." "She is to stay here in London, then?" asked Ricardo. "Oh, yes; she is not to go. She will present her letters at the Opera House and secure an engagement, if she can. The criminals might be lulled thereby into a belief that the girl had kept the whole strange incident to herself, and that there was nowhere even a knowledge of the disguise which they had used." Hanaud spoke as carelessly as if the matter was not very important; and Ricardo, with an unusual flash of shrewdness, said: "It is clear, my friend, that you do not think those two men will ever be caught at all." Hanaud shrugged his shoulders. "There is always a chance. But listen. There is a room with a hundred guns, one of which is loaded. Outside the room there are a hundred pigeons, one of which is white. You are taken into the room blind-fold. You choose the loaded gun and you shoot the one white pigeon. That is the value of the chance." "But," exclaimed Ricardo, "those pearls were of great value, and I have heard at a trial expert evidence given by pearl merchants. All agree that the pearls of great value are known; so, when they come upon the market----" "That is true," Hanaud interrupted imperturbably. "But how are they known?" "By their weight," said Mr. Ricardo. "Exactly," replied Hanaud. "But did you not also hear at this trial of yours that pearls can be peeled like an onion? No? It is true. Remove a skin, two skins, the weight is altered, the pearl is a trifle smaller. It has lost a little of its value, yes--but you can no longer identify it as the so-and-so pearl which belonged to this or that sultan, was stolen by the vizier, bought by Messrs. Lustre and Steinopolis, of Hatton Garden, and subsequently sold to the wealthy Mrs. Blumenstein. No, your pearl has vanished altogether. There is a new pearl which can be traded." He looked at Ricardo. "Who shall say that those pearls are not already in one of the queer little back streets of Amsterdam, undergoing their transformation?"