“We never should have found it but for our mother’s story,” said Gaston, with exultation in his voice.  “Raymond, methinks that this is the first step in our career of vengeance.  We have the key to Basildene in our hands.  It may be that upon another occasion we may use it with a different purpose.”

It seemed to the brothers that they had walked a great distance, when their steps were arrested by what appeared in the first instance to be a solid wall of stone.  Had they not had some sort of clue in their heads, they would certainly have believed that this natural tunnel ended here, and that further progress was impossible.  But as it was, they were firmly convinced that this was but the door of masonry of which their mother had told them in years gone by.  Neither could recollect the story save in fragments; but the numbers had clung to Gaston’s tenacious memory, and now he stood before the door saying again and again —­ “Seven from the top, three from the bottom” —­ scanning the wall in front of him with the keenest glances all the while.

“Ha!” he exclaimed at length; “bring the torch nearer, Raymond.  See here.  This is not one block of stone, as seems at first, but a mass of masonry so cunningly joined together as to look like one solid piece.  See, here are the joints; I can feel them with my fingernail, though I can scarce see them with my eyes.  Let us count the number of the stones used.  Yes; there are nine in all from top to bottom, each of the same width.  Therefore the seventh from the top is the third counting from the bottom.  This is the stone which is the key.”

So saying, Gaston set his knee against it and pressed with all his might.  Almost to his own surprise he felt it give as he did so, and Raymond uttered a short cry of astonishment:  for the whole of what had looked like a solid wall revolved slowly inwards, revealing a continuation of the passage which they had been traversing so long, only that now the passage was plainly one in the interior of the house; for the walls were of masonry, and the dimensions were far more regular.

“This is the secret door,” said Gaston exultingly.  “It is in truth a cunning contrivance.  Let me have the light here a moment, Brother.  I will see what the trick of the door upon this side is.”

This point was quickly settled by an inspection of the ingenious contrivance, which was one purely of balance, and not dependent either upon springs or bolts.  Probably it dated back from days when these latter things were hardly known, and was so satisfactory in the working that it had never been improved upon.

“The way to Basildene is always open to us,” murmured Raymond, with a quick thrill of exultation, as the brothers passed through the doorway and let it close behind them; and then they forgot all else in the excitement of the search after the woodman’s miserable son.