Madame d’Arlange was naturally not aware that her remark implied the most exquisite torture for Lecoq.  Ah! if it should be as she said, if he should never find the lady who had lost this costly jewel!  Smarting under the marchioness’s unintended irony, he would have liked to apostrophize her in angry terms; but it could not be, for it was advisable if not absolutely necessary that he should conceal his true identity.  Accordingly, he contrived to smile, and even stammered an acknowledgment of Madame d’Arlange’s good wishes.  Then, as if he had no more to expect, he made her a low bow and withdrew.

This new misfortune well-nigh overwhelmed him.  One by one all the threads upon which he had relied to guide him out of this intricate labyrinth were breaking in his hands.  In the present instance he could scarcely be the dupe of some fresh comedy, for if the murderer’s accomplice had taken Doisty, the jeweler, into his confidence he would have instructed him to say that the earring had never come from his establishment, and that he could not consequently tell whom it had been sold to.  On the contrary, however, Doisty and his wife had readily given Madame d’Arlange’s name, and all the circumstances pointed in favor of their sincerity.  Then, again, there was good reason to believe in the veracity of the marchioness’s assertions.  They were sufficiently authenticated by a significant glance which Lecoq had detected between the jeweler and his wife.  The meaning of this glance could not be doubted.  It implied plainly that both husband and wife were of opinion that in buying these earrings the marchioness engaged in one of those little speculations which are more common than many people might suppose among ladies moving in high-class society.  Being in urgent want of ready money, she had bought on credit at a high price to sell for cash at a loss.

As Lecoq was anxious to investigate the matter as far as possible, he returned to Doisty’s establishment, and, by a plausible pretext, succeeded in gaining a sight of the books in which the jeweler recorded his transactions.  He soon found the sale of the earrings duly recorded—­specified by Madame Doisty at the date—­both in the day-book and the ledger.  Madame d’Arlange first paid 9,000 francs on account and the balance of the purchase money (an equivalent sum) had been received in instalments at long intervals subsequently.  Now, if it had been easy for Madame Milner to make a false entry in her traveler’s registry at the Hotel de Mariembourg, it was absurd to suppose that the jeweler had falsified all his accounts for four years.  Hence, the facts were indisputable; and yet, the young detective was not satisfied.

He hurried to the Faubourg Saint Honore, to the house formerly occupied by the Baroness de Watchau, and there found a good-natured concierge, who at once informed him that after the Baroness’s death her furniture and personal effects had been taken to the great auction mart in the Rue Drouot; the sale being conducted by M. Petit, the eminent auctioneer.