thick masonry of the wall; the one at the opposite end seemed built into
the solid rock.

"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 this time, I had
been obliged to carry about my person. And now, forward to the heart of
the mystery!"