The grin left Peter's face, and his eyes narrowed. He had, indeed, found food for thought. A joint account, for about fifty thousand dollars, which would be entirely under Anne's control if Mary--should die. Had he found a motive, a sufficient motive? And why had Anne drawn so large a sum on Saturday? Saturday! The very day before the one on which Anne and Mary had both vanished, leaving no trace. Did someone know of the large sum in currency which the sisters had in their apartment, presumably, on Saturday night?... But Anne, at least, had left the apartment, herself unharmed, on Sunday evening. That was an established fact. And why hadn't Anne made use of the safe and convenient A.B.A. checks, as the paying teller had advised her? She had evidently considered doing so, for she had examined the blanks--and found, not only that she must sign them first when purchasing, but also that the signature at the bottom must agree with the one in the body of the check when it was cashed. There was only one possible conclusion in the detective's mind. She did not wish to use her own name, and that was why she would not buy them of the bank where she was known. If she was clever, she would see that she could purchase the checks elsewhere and use any name she saw fit. Peter was confident that when, or if, they found Anne Blake, it would be under some other name. These reflections occupied but a moment, so swift were Peter's mental processes. He had noted and tabulated each circumstance for future application to the problem in hand, and there had been scarcely a perceptible pause in the conversation when he said: "I'm awfully obliged to you, Mr. Dunne, for the information you've given me. There's just one thing more. Would you mind showing me any vouchers you may happen to have on Miss Blake's account? It would be a great favour." The cashier pursed his lips, and shook his head. "I'm afraid I really couldn't do that, Mr. Clancy," he said, apologetically. "Cancelled checks are the property of the client, and not of the bank. I could show you the signature card, if you'd be interested in that. It shows both signatures, if that's what you want to see." Peter did not care to explain that he had hoped to get from the vouchers some clue which would indicate with whom the sisters were accustomed to have dealings, or that he might stumble on some other valuable bit of information. This proving impossible, he might as well look at the signatures. As O'Malley always said, "You never can tell----" "Why, thanks. I would like to see them, Mr. Dunne," he said, "if it isn't too much trouble." "Not a bit," responded the cashier, rising. He passed again behind the network of grilles, and presently returned with the usual signature card in his hand. Seating himself, he laid it before the detective.