''On all sides there is treachery. I _demand_, sir, an explanation. What leads you to associate the name of that firm with this matter? Either you are our friend or you are not. Speak plainly!' ''Madame, by the merest chance, I overheard Pedro mention those names, and since you have given me your confidence, I will give you some information which may put you on your guard, and help to guide your future plans.' 'I then briefly related the conversations I had overheard between General Valiente and Pedro, both on the Alameda and in the gaming-house in the Calle del Arco. ''Now, madame,' I continued, 'let me inquire whether the Mexican from whom you derived your information, had any connection with this firm?' ''Yes, sir, he knew them,' she replied; then, after a slight pause, she added: 'We have already told you so much that it would be folly to conceal the way in which we became acquainted with the existence of this mine. Soon after my marriage, I met a veteran officer of the Mexican army, General Ramiro, then living in exile, at New-Orleans. For me he conceived a paternal affection, and many a time remonstrated with Mr. Percival, and entreated him to devote himself to his family, and abandon the course of life which was leading him to ruin. He often spoke of his desire to return to Mexico, and lived constantly in the hope of the decree being revoked, which had driven him into exile. One day he disclosed the chief cause of his desire to return, by revealing the secret we have imparted to you.' ''Pardon me, madame,' I said, 'but tell me how General Ramiro gained his information? Exploring for opal mines is hardly part of the duties of a General, even in Mexico.' ''I was about to explain that,' replied the lady. 'An Indian, convicted of murdering a monk, some three years previously, was condemned to death. On being taken, according to Mexican usage, on the eve of execution, to the confessional, he refused the slightest attention to the exhortations of the priests, affirming that he had written a letter to the Governor, which would secure his pardon. ''True enough, a party of dragoons arrived during the night, and took him away. The letter was addressed to General Ramiro, then acting as Governor, and contained promises of a revelation of the highest importance. ''When conducted to the General, the Indian proved, by a host of details, the existence of an opal mine, which he had accidentally discovered, and in return for the revelation, demanded a free pardon.' ''I understand, perfectly, madame,' I added, seeing Adéle hesitate. ''I feel,' she said, 'a certain reluctance at this portion of my narrative, for it forces me to lay bare an act which General Ramiro ever after regretted, and which--' ''Madame, I will spare you the recital; the fact is, the General gained the Indian's secret, and then--unfortunately for the Indian--forgot to fulfill his promise.'