"I do sometimes," he said, tapping his pocket. "We might come up against danger if my theory is correct. If I tell you to shoot--shoot, and quickly. Your life is likely to depend upon it. And keep your ears open to make sure no one is following us."

He had become keen, like a dog on the trail, and, old as he was, seemed incapable of fatigue. Whether he had studied the topography of the neighborhood I cannot say, but he did not hesitate in his direction until he reached a high knoll which was clear of the wood and commanded a considerable view.

We were trespa.s.sers in a private park. To our right was a large house, only partially seen through its screen of trees, but it was evidently mellow with age. To our left, toward what was evidently the extremity of the park, was hilly ground, which had been allowed to run wild.

To this Quarles pointed.

"That is our way," he said. "We'll use what cover we can."

We plunged into the wood again, and were soon in the wilderness, forcing our way, sometimes with considerable difficulty, through the undergrowth. Once or twice the professor gave me a warning gesture, but he did not speak. He had evidently some definite goal, and I was conscious of excitement as I followed him.

For an hour or more he turned this way and that, exploring every little ravine he could discover, grunting his disappointment each time he failed to find what he was looking for.

"I said I wasn't certain," he whispered when our path had led us into a damp hollow which looked as if it had not been visited by man for centuries. "My theory seems--and yet this is such a likely place.

There must be a way."

He was going forward again. The hollow was surrounded by perpendicular walls of sand and chalk; it was a pit, in fact, which Nature had filled with vegetation. The way we had come seemed the only way into it.

"Ah! this looks promising," Quarles said suddenly.

In a corner of the wall, or, to be more precise, filling up a rent in it, was a shed, roughly built, but with a door secured by a very business-like lock.

"I think the shed is climbable," said Quarles. "Let's get on the roof.

I am not so young as I was, so help me up."

It was not much help he wanted. In a few moments we were on the roof.

"As I thought," he said. "Do you see?"

The shed, with its slanting roof, served to block a narrow, overgrown path between two precipitous chalk walls.

"We'll go carefully," said Quarles. "There may be worse than poachers'

traps here."

Without help from me he dropped from the roof, and I followed him.

The natural pa.s.sage was winding, and about fifty yards long, and opened into another pit of some size. A pit I call it, but it was as much a cave as a pit, part of it running deeply into the earth, and only about a third of it being open to the sky. The cave part had a rough, sandy floor, and here was a long shed of peculiar construction.

It was raised on piles, about eight feet high; the front part formed a kind of open veranda, the back part being closed in. The roof was thatched with bark and dried bracken, and against one end of the veranda was a notched tree trunk, serving as a ladder.

"As I expected," said Quarles, with some excitement. "We must get onto the veranda for a moment. I think we are alone here, but keep your ears open."

The shed was evidently used sometimes. There was a stone slab which had served as a fireplace, and from a beam above hung a short chain, on which a pot could easily be fixed.

"We'll get away quickly," said Quarles. "Patience, Wigan. I believe we are going to witness a wonderful thing."

"When?"

"In about thirty hours' time."

The professor's sense of direction was marvelous. Having reclimbed the shed which blocked the entrance to this concealed pit, he made practically a straight line for the place at which we had entered the wood from the road.

"I daresay one would be allowed to see over the house, but perhaps it is as well not to ask," he said. "We can do that later. I'm tired, Wigan; but it was safer not to keep the carriage."

Try as I would, I could get no explanation out of him either that night or next day. He was always as secret as the grave until he had proved his theory, and then he seemed anxious to forget the whole affair, and shrank from publicity. That is how it came about that I obtained credit which I did not deserve.

"We go there again this evening," he said after lunch next day; "so a restful afternoon will suit us."

It was getting dark when we set out, and again Quarles's unerring sense of locality astonished me. He led the way without hesitation.

This time he took more precaution not to make a sound when climbing over the shed into the narrow path.

"I think we are first, but great care is necessary," he whispered.

We crept forward and concealed ourselves among the scrub vegetation which grew in that part of the pit which was open to the sky. It was dark, the long shed barely discernible, but the professor was particular about our position.

"We may have to creep a little nearer presently," he whispered. "From here we can do so. Silence, Wigan, and don't be astonished at anything."

The waiting seemed long. Moonlight was presently above us, throwing the cave part of the pit into greater shadow than ever.

I cannot attempt to say how long we had waited in utter silence when Quarles touched my arm. Someone was coming, and with no particular stealth. Whoever it was seemed quite satisfied that the night was empty of danger. I heard footsteps on the raised floor of the shed--a man's step, and only one man's. I heard him moving about for some time. I think he came down the ladder once and went up again. Then there was a light and sudden tiny flames. In the dark he had evidently got fuel, and had started a fire on the stone slab.

As the flames brightened I watched his restless figure. He was not a young man. I caught a glimpse of white hair, but he took no position in which I could see his face clearly. He was short, thick-set, and quick in his movements.

From somewhere at the back of the shed he pushed forward a block of wood, and, standing on this, he fixed something to the short chain I had noted yesterday. When he got down again I saw that a bundle was suspended over the fire, not a pot, and it was too high for the flames or much of the heat to reach it, only the smoke curled about it.

Then the man moved the wooden block to the side of the fire and sat down facing us, the flickering flames throwing a red glow over him.

"Wigan, do you see?" whispered Quarles.

"Not clearly."

"We'll go nearer. Carefully."

From our new point of view I looked again. The man's face was familiar, but just then I could not remember who he was. It was the bundle hanging over the fire which fascinated me.

Tied together, and secured in a network of string, were five or six human heads, blackened, shriveled faces, which seemed to grin horribly as they swung deeply from side to side, lit up by the flicker of the flames.

"Do you see, Wigan?" Quarles asked again.

"Yes."

"And the man?"

"Who is he?"

"On the bench yesterday. Sir Henry Buckingham. Don't you remember?"

For an hour--two, three, I don't know how long--that horrible bundle swung over the fire, and the man sat on his block of wood, staring straight before him. I had a great desire to rush from my hiding-place and seize him, and I waited, expecting some further revelation, listening for other footsteps. None came. The fire flickered lower and went out. The moon had set, and the cold of the early morning got into my bones.