“It’s a very rare bird - practically extinct - in England now, but all things are possible upon the moor. Yes, I should not be surprised to learn that what we have heard is the cry of the last of the bitterns.”

“It’s the weirdest, strangest thing that ever I heard in my life.”

“Yes, it’s rather an uncanny place altogether. Look at the hillside yonder. What do you make of those?”

The whole steep slope was covered with gray circular rings of stone, a score of them at least.

“What are they? Sheep-pens?”

“No, they are the homes of our worthy ancestors. Prehistoric man lived thickly on the moor, and as no one in particular has lived there since, we find all his little arrangements exactly as he left them. These are his wigwams with the roofs off. You can even see his hearth and his couch if you have the curiosity to go inside.”

“But it is quite a town. When was it inhabited?”

“Neolithic man - no date.”

“What did he do?”

“He grazed his cattle on these slopes, and he learned to dig for tin when the bronze sword began to supersede the stone axe. Look at the great trench in the opposite hill. That is his mark. Yes, you will find some very singular points about the moor, Dr. Watson. Oh, excuse me an instant! It is surely Cyclopides.”

A small fly or moth had fluttered across our path, and in an instant Stapleton was rushing with extraordinary energy and speed in pursuit of it. To my dismay the creature flew straight for the great mire, and my acquaintance never paused for an instant, bounding from tuft to tuft behind it, his green net waving in the air. His gray clothes and jerky, zigzag, irregular progress made him not unlike some huge moth himself. I was standing watching his pursuit with a mixture of admiration for his extraordinary activity and fear lest he should lose his footing in the treacherous mire when I heard the sound of steps and, turning round, found a woman near me upon the path. She had come from the direction in which the plume of smoke indicated the position of Merripit House, but the dip of the moor had hid her until she was quite close.

I could not doubt that this was the Miss Stapleton of whom I had been told, since ladies of any sort must be few upon the moor, and I remembered that I had heard someone describe her as being a beauty. The woman who approached me was certainly that, and of a most uncommon type. There could not have been a greater contrast between brother and sister, for Stapleton was neutral tinted, with light hair and gray eyes, while she was darker than any brunette whom I have seen in England - slim, elegant, and tall. She had a proud, finely cut face, so regular that it might have seemed impassive were it not for the sensitive mouth and the beautiful dark, eager eyes. With her perfect figure and elegant dress she was, indeed, a strange apparition upon a lonely moorland path. Her eyes were on her brother as I turned, and then she quickened her pace towards me. I had raised my hat and was about to make some explanatory remark when her own words turned all my thoughts into a new channel.

“Go back!” she said. “Go straight back to London, instantly.”

I could only stare at her in stupid surprise. Her eyes blazed at me, and she tapped the ground impatiently with her foot.

“Why should I go back?” I asked.

“I cannot explain.” She spoke in a low, eager voice, with a curious lisp in her utterance. “But for God’s sake do what I ask you. Go back and never set foot upon the moor again.”

“But I have only just come.”