"Before we go any farther," said Platzoff, "I may as well explain to you how it happens that a respectable old country-house like Bon Repos has such a suspicious-looking hiding-place about its premises. You must know that I bought the house, many years ago, of the last representative of an old north-country family. He was a bachelor, and in him the family died out. Three years after I had come to reside here the old man, at that time on his death-bed, sent me a letter and a key. The letter revealed to me the secret of the place we are now exploring, of which I had no previous knowledge; the key is that of the two iron doors. It seems that the old man's ancestors had been deeply implicated in the Jacobite risings of last century. The house had been searched several times, and on one occasion occupied by Hanoverian troops. As a provision against such contingencies this hiding-place (a natural one as far as the cavern beyond is concerned, which has probably existed for thousands of years) was then first connected with the interior of the house, and rendered practicable at a moment's notice; and here on several occasions, certain members of the family, together with their plate and title-deeds, lay concealed for weeks at a time. The old gentleman gave me a solemn assurance that the secret existed with him alone; all who had been in any way implicated in the earlier troubles having died long ago. As the property had now become mine by purchase, he thought it only right that before he died these facts should be brought to my knowledge. You may imagine, my dear Ducie, with what eagerness I seized upon this place as a safe depository for my Diamond, which, up to that time, I had been obliged to carry about my person. And now, forward to the heart of the mystery!" Having unlocked and flung open the second iron door, Platzoff took up his lamp, and, closely followed by Ducie, entered a narrow winding passage in the rock. After following this passage, which tended slightly downwards for a considerable distance, they emerged into a large cavernous opening in the heart of the hill.