By one o’clock he had been round the whole six, and as he sat lunching in a small French restaurant off Cranbourne Street, he thought over what he had learned. In each shop, after more or less delay, he had found the salesman who had served Mrs. X. All six men remembered her, and her proceedings with each seemed to have been the same. In each case she had asked for a piece of jewellery for a dear friend who was going to be married—something plain, but good; a diamond ring or a jewelled bangle or some costly trifle which would please a young girl’s fancy. In each shop her purchases came to somewhere between two and three hundred pounds, and in each case she had proffered a cheque. She had volunteered to wait while a messenger was sent to the bank, as she had admitted that she couldn’t expect the shop people to take her cheque when they didn’t know her. The salesmen had all protested that this was unnecessary, and had politely kept her talking while they took the precaution. Finally, a telephone from the bank having reassured them, they had handed her her purchase and bowed her out. None of them had either noticed or suspected anything unusual in the transactions, and all were satisfied everything about them was O. K. French was considerably puzzled by the whole business, but under the stimulus of a cup of coffee, a possible theory flashed into his mind. Was it not probable that this purchase of costly but commonplace articles of jewellery at six different shops was simply a part of the plan to transform Mr. Duke’s sixteen stones into money? As he thought over it, French thought he could dimly grasp that plan as a whole. First, the minds of Mr. Williams and of Mr. Hurst were prepared for what was coming by a previous visit. It was impossible that any suspicion could attach to that first visit, as when it was paid the robbery had not taken place. And now French saw that, but for the accident of the clerk, Orchard, visiting the office, these two gentlemen would not have known anything about the robbery when the second call was made, a distinctly clever achievement from the criminal’s point of view. However, be that as it might, Mrs. X’s bluff carried her through, and she exchanged her stones, or rather Mr. Duke’s, for Mr. Williams’s cheque. But she was evidently afraid to cash the whole of the cheque, and French saw her point, namely, that the opening of an account and the lodging of £1500 was an astute move, calculated to prevent the suspicion that might possibly be caused by the cashing of £3000 in small notes. But this safeguard left her with the necessity of devising a plan for cashing her deposit, and here, in the purchase of the jewellery, French saw the plan. _Would she not sell what she had just bought?_ If she could do so, there was the whole £3000 changed into untraceable notes.