"I fancy I can even explain that, dear. My uncle came down suddenly to-day from London. He wanted certain papers in a great hurry. Now, those papers were locked up in a drawer at 219 given over specially to Mr. Henson. My uncle promptly broke open the drawer and took out the papers. Besides those documents the drawer contained a package in one of Lockhart's big linen-lined envelopes—a registered letter envelope, in fact. My uncle had little time to spare, as he was bound to be back in London to-night. He suggested that as the back of the drawer was broken and the envelope presumably contained valuables, I had better take care of it. Well, I must admit at once that I steamed the envelope open. I shouldn't have done so if Lockhart's name had not been on the flap. In a little case inside I found a diamond bracelet, which I have in my pocket, together with a receipted bill for seventy odd pounds made out to me."
"To you?" David cried. "Do you mean to say that—"
"Indeed I do. The receipt was made out to me, and with it was a little polite note to the effect that Messrs. Lockhart had made the exchange of the cigar-case for the diamond bracelet, and that they hoped Miss Gates would find the matter perfectly satisfactory."
David was too astonished to say anything for the moment. The skein was too tangled to be thought out all at once. Presently he began to see his way.
"Under ordinary circumstances the change seems impossible," he said. "Especially seeing that the juggling could not have been done without both the cases—but I had forgotten how easily the cases were changed. I have it! What is the date of that letter?"
Ruth slowly unfolded a document she had taken from her purse.
"The day following what you call your great adventure," she said. "Henson or somebody took the real case—my case—back to Lockhart's and changed it in my name. I had previously been admiring this selfsame bracelet, and they had tried to sell it to me. My dear boy, don't you see this is all part of the plot to plunge you deeper and deeper into trouble, to force us all to speak to save you? There are at least fifteen assistants at Lockhart's. Of course the ultimate sale of the cigar-case to this American could be proved, seeing that the case had got back into stock again, and at the same time the incident of the change quite forgotten. And when you go and ask questions at Lockhart's—as you were pretty sure to do, as Henson knew—you are told of the sale only to the American. Depend upon it, that American was Henson himself or somebody in his pay. David, that man is too cunning, too complex. And some of these days it is going to prove his fall."
David nodded thoughtfully. And yet, without something very clever and intricate in the way of a scheme, Henson could not have placed him in his present fix.
"There is only one thing to be done," he said. "You and I must go down to Lockhart's and make a few inquiries. With that diamond bracelet and letter in your possession you should have no difficulty in refreshing their memories. Will you have some tea?"
"I am too excited," Ruth laughed. "I couldn't eat or drink anything just at present. David, what a lovely house you have."