“I think there must have been some room with a way into it.  I remember going up some steep steps; they must have been worn smooth by long use or something of the kind, for I could hardly keep my feet as I went up.  Once I stumbled and nearly fell into the well-hole.”

“Was there anything strange about the place—­any queer smell, for instance?”

“Queer smell—­yes!  Like bilge or a rank swamp.  It was distinctly nauseating; when I came out I felt as if I had just been going to be sick.  I shall try back on my visit and see if I can recall any more of what I saw or felt.”

“Then perhaps, sir, later in the day you will tell me anything you may chance to recollect.”

“I shall be delighted, Adam.  If your uncle has not returned by then, I’ll join you in the study after dinner, and we can resume this interesting chat.”

CHAPTER XVII—­THE MYSTERY OF “THE GROVE”

That afternoon Adam decided to do a little exploring.  As he passed through the wood outside the gate of Diana’s Grove, he thought he saw the African’s face for an instant.  So he went deeper into the undergrowth, and followed along parallel to the avenue to the house.  He was glad that there was no workman or servant about, for he did not care that any of Lady Arabella’s people should find him wandering about her grounds.  Taking advantage of the denseness of the trees, he came close to the house and skirted round it.  He was repaid for his trouble, for on the far side of the house, close to where the rocky frontage of the cliff fell away, he saw Oolanga crouched behind the irregular trunk of a great oak.  The man was so intent on watching someone, or something, that he did not guard against being himself watched.  This suited Adam, for he could thus make scrutiny at will.

The thick wood, though the trees were mostly of small girth, threw a heavy shadow, so that the steep declension, in front of which grew the tree behind which the African lurked, was almost in darkness.  Adam drew as close as he could, and was amazed to see a patch of light on the ground before him; when he realised what it was, he was determined, more than ever to follow on his quest.  The nigger had a dark lantern in his hand, and was throwing the light down the steep incline.  The glare showed a series of stone steps, which ended in a low-lying heavy iron door fixed against the side of the house.  All the strange things he had heard from Sir Nathaniel, and all those, little and big, which he had himself noticed, crowded into his mind in a chaotic way.  Instinctively he took refuge behind a thick oak stem, and set himself down, to watch what might occur.